diff --git a/doc/reference/src/aop-aspect-library.xml b/doc/reference/src/aop-aspect-library.xml
index 313e6755..2b198ac1 100644
--- a/doc/reference/src/aop-aspect-library.xml
+++ b/doc/reference/src/aop-aspect-library.xml
@@ -196,14 +196,14 @@ public <classname>Airport</classname> GetAirport(long id)
 
     <para>The first parameter is the cache name. The second string parameter
     is the cache key and is a string expression that incorporates the argument
-    passed into the method, the id. The method parameter names are exposed as
-    variables to the key expression. If you do not specify a key, then all the
-    parameter values will be used to cache the returned value. The expression
-    may also call out to other objects in the Spring container allowing for a
-    more complex key algorithm to be encapsulated. The end result is that the
-    Airport object is cached by id for 60 seconds in a cache named
-    AspNetCache. The TimetoLive property could also have been specified on the
-    configuration of the AspNetCache object.</para>
+    passed into the method, the id. The cache key value cannot be null or an
+    empty string (""). The method parameter names are exposed as variables to
+    the key expression. The expression may also call out to other objects in
+    the Spring container allowing for a more complex key algorithm to be
+    encapsulated. The end result is that the Airport object is cached by id
+    for 60 seconds in a cache named AspNetCache. The TimetoLive property could
+    also have been specified on the configuration of the AspNetCache
+    object.</para>
 
     <para>The configuration to enable the caching aspect is shown below</para>
 
diff --git a/src/Spring/Spring.Core/Caching/BaseCacheAttribute.cs b/src/Spring/Spring.Core/Caching/BaseCacheAttribute.cs
index 62a25e00..130a7bc0 100644
--- a/src/Spring/Spring.Core/Caching/BaseCacheAttribute.cs
+++ b/src/Spring/Spring.Core/Caching/BaseCacheAttribute.cs
@@ -1,174 +1,186 @@
-using System;
-using Spring.Core.TypeConversion;
-using Spring.Expressions;
-
-namespace Spring.Caching
-{
-    /// <summary>
-    /// Abstract base class containing shared properties for all cache attributes.
-    /// </summary>
-    /// <author>Aleksandar Seovic</author>
-    [Serializable]
-    public abstract class BaseCacheAttribute : Attribute
-    {
-        #region Fields
-
-        /// <summary>
-        /// The <see cref="TimeSpanConverter"/> instance used to parse <see cref="TimeSpan"/> values.
-        /// </summary>
-        /// <see cref="TimeToLive"/>
-        /// <see cref="TimeToLiveTimeSpan"/>
-        protected static readonly TimeSpanConverter TimeSpanConverter = new TimeSpanConverter();
-
-        private string cacheName;
-        private string key;
-        private IExpression keyExpression;
-        private string condition;
-        private IExpression conditionExpression;
-        private string timeToLive = null;
-        private TimeSpan timeToLiveTimeSpan = TimeSpan.MinValue;
-
-        #endregion
-
-        #region Constructors
-
-        /// <summary>
-        /// Creates an attribute instance.
-        /// </summary>
-        public BaseCacheAttribute()
-        {
-        }
-
-        /// <summary>
-        /// Creates an attribute instance.
-        /// </summary>
-        /// <param name="cacheName">
-        /// The name of the cache to use.
-        /// </param>
-        /// <param name="key">
-        /// An expression string that should be evaluated in order to determine
-        /// the cache key for the item.
-        /// </param>
-        public BaseCacheAttribute(string cacheName, string key)
-        {
-            this.CacheName = cacheName;
-            this.Key = key;
-        }
-
-        #endregion
-
-        #region Properties
-
-        /// <summary>
-        /// Gets or sets the name of the cache to use.
-        /// </summary>
-        /// <value>
-        /// The name of the cache to use.
-        /// </value>
-        public string CacheName
-        {
-            get { return cacheName; }
-            set { cacheName = value; }
-        }
-
-        /// <summary>
-        /// Gets or sets a SpEL expression that should be evaluated in order 
-        /// to determine the cache key for the item.
-        /// </summary>
-        /// <value>
-        /// An expression string that should be evaluated in order to determine
-        /// the cache key for the item.
-        /// </value>
-        public string Key
-        {
-            get { return key; }
-            set
-            {
-                key = value;
-                keyExpression = Expression.Parse(value);
-            }
-        }
-
-        /// <summary>
-        /// Gets an expression instance that should be evaluated in order 
-        /// to determine the cache key for the item.
-        /// </summary>
-        /// <value>
-        /// An expression instance that should be evaluated in order to determine
-        /// the cache key for the item.
-        /// </value>
-        public IExpression KeyExpression
-        {
-            get { return keyExpression; }
-        }
-
-        /// <summary>
-        /// Gets or sets a SpEL expression that should be evaluated in order 
-        /// to determine whether the item should be cached.
-        /// </summary>
-        /// <value>
-        /// An expression string that should be evaluated in order to determine
-        /// whether the item should be cached.
-        /// </value>
-        public string Condition
-        {
-            get { return condition; }
-            set
-            {
-                condition = value;
-                conditionExpression = Expression.Parse(value);
-            }
-        }
-
-        /// <summary>
-        /// Gets an expression instance that should be evaluated in order 
-        /// to determine whether the item should be cached.
-        /// </summary>
-        /// <value>
-        /// An expression instance that should be evaluated in order to determine
-        /// whether the item should be cached.
-        /// </value>
-        public IExpression ConditionExpression
-        {
-            get { return conditionExpression; }
-        }
-
-        /// <summary>
-        /// The amount of time an object should remain in the cache.
-        /// </summary>
-        /// <remarks>
-        /// If no TTL is specified, the default TTL defined by the 
-        /// cache's policy will be applied.
-        /// </remarks>
-        /// <value>
-        /// The amount of time object should remain in the cache 
-        /// formatted to be recognizable by <see cref="TimeSpan.Parse(string)"/>.
-        /// </value>
-        public string TimeToLive
-        {
-            get { return timeToLive; }
-            set
-            {
-                timeToLive = value;
-                timeToLiveTimeSpan = (timeToLive == null) ? TimeSpan.MinValue : (TimeSpan)TimeSpanConverter.ConvertFrom(timeToLive);
-            }
-        }
-
-
-        /// <summary>
-        /// The amount of time an object should remain in the cache (in seconds).
-        /// </summary>
-        /// <remarks>
-        /// If no TTL is specified, the default TTL defined by the 
-        /// cache's policy will be applied.
-        /// </remarks>
-        /// <value>
-        /// The amount of time object should remain in the cache (in seconds).
-        /// </value>
-        public TimeSpan TimeToLiveTimeSpan
-        {
-            get { return timeToLiveTimeSpan; }
-        }
-
-        #endregion
    }
+using System;
+using Spring.Core.TypeConversion;
+using Spring.Expressions;
+
+namespace Spring.Caching
+{
+    /// <summary>
+    /// Abstract base class containing shared properties for all cache attributes.
+    /// </summary>
+    /// <author>Aleksandar Seovic</author>
+    [Serializable]
+    public abstract class BaseCacheAttribute : Attribute
+    {
+        #region Fields
+
+        /// <summary>
+        /// The <see cref="TimeSpanConverter"/> instance used to parse <see cref="TimeSpan"/> values.
+        /// </summary>
+        /// <see cref="TimeToLive"/>
+        /// <see cref="TimeToLiveTimeSpan"/>
+        protected static readonly TimeSpanConverter TimeSpanConverter = new TimeSpanConverter();
+
+        private string cacheName;
+        private string key;
+        private IExpression keyExpression;
+        private string condition;
+        private IExpression conditionExpression;
+        private string timeToLive = null;
+        private TimeSpan timeToLiveTimeSpan = TimeSpan.MinValue;
+
+        #endregion
+
+        #region Constructors
+
+        /// <summary>
+        /// Creates an attribute instance.
+        /// </summary>
+        public BaseCacheAttribute()
+        {
+        }
+
+        /// <summary>
+        /// Creates an attribute instance.
+        /// </summary>
+        /// <param name="cacheName">
+        /// The name of the cache to use.
+        /// </param>
+        /// <param name="key">
+        /// An expression string that should be evaluated in order to determine
+        /// the cache key for the item.
+        /// </param>
+        /// <remarks>The cache key cannot evaluate be null or an empty string.</remarks>
+        public BaseCacheAttribute(string cacheName, string key)
+        {
+            if (null == key)
+            {
+                throw new ArgumentNullException("key", "The expression for the Cache Key cannot be null.");
+            }
+
+            if (key.Trim() == string.Empty)
+            {
+                throw new ArgumentOutOfRangeException("key", "The expression for the Cache Key cannot be an empty string.");
+            }
+
+            this.CacheName = cacheName;
+            this.Key = key;
+        }
+
+        #endregion
+
+        #region Properties
+
+        /// <summary>
+        /// Gets or sets the name of the cache to use.
+        /// </summary>
+        /// <value>
+        /// The name of the cache to use.
+        /// </value>
+        public string CacheName
+        {
+            get { return cacheName; }
+            set { cacheName = value; }
+        }
+
+        /// <summary>
+        /// Gets or sets a SpEL expression that should be evaluated in order 
+        /// to determine the cache key for the item.
+        /// </summary>
+        /// <value>
+        /// An expression string that should be evaluated in order to determine
+        /// the cache key for the item.
+        /// </value>
+        public string Key
+        {
+            get { return key; }
+            set
+            {
+                key = value;
+                keyExpression = Expression.Parse(value);
+            }
+        }
+
+        /// <summary>
+        /// Gets an expression instance that should be evaluated in order 
+        /// to determine the cache key for the item.
+        /// </summary>
+        /// <value>
+        /// An expression instance that should be evaluated in order to determine
+        /// the cache key for the item.
+        /// </value>
+        public IExpression KeyExpression
+        {
+            get { return keyExpression; }
+        }
+
+        /// <summary>
+        /// Gets or sets a SpEL expression that should be evaluated in order 
+        /// to determine whether the item should be cached.
+        /// </summary>
+        /// <value>
+        /// An expression string that should be evaluated in order to determine
+        /// whether the item should be cached.
+        /// </value>
+        public string Condition
+        {
+            get { return condition; }
+            set
+            {
+                condition = value;
+                conditionExpression = Expression.Parse(value);
+            }
+        }
+
+        /// <summary>
+        /// Gets an expression instance that should be evaluated in order 
+        /// to determine whether the item should be cached.
+        /// </summary>
+        /// <value>
+        /// An expression instance that should be evaluated in order to determine
+        /// whether the item should be cached.
+        /// </value>
+        public IExpression ConditionExpression
+        {
+            get { return conditionExpression; }
+        }
+
+        /// <summary>
+        /// The amount of time an object should remain in the cache.
+        /// </summary>
+        /// <remarks>
+        /// If no TTL is specified, the default TTL defined by the 
+        /// cache's policy will be applied.
+        /// </remarks>
+        /// <value>
+        /// The amount of time object should remain in the cache 
+        /// formatted to be recognizable by <see cref="TimeSpan.Parse(string)"/>.
+        /// </value>
+        public string TimeToLive
+        {
+            get { return timeToLive; }
+            set
+            {
+                timeToLive = value;
+                timeToLiveTimeSpan = (timeToLive == null) ? TimeSpan.MinValue : (TimeSpan)TimeSpanConverter.ConvertFrom(timeToLive);
+            }
+        }
+
+
+        /// <summary>
+        /// The amount of time an object should remain in the cache (in seconds).
+        /// </summary>
+        /// <remarks>
+        /// If no TTL is specified, the default TTL defined by the 
+        /// cache's policy will be applied.
+        /// </remarks>
+        /// <value>
+        /// The amount of time object should remain in the cache (in seconds).
+        /// </value>
+        public TimeSpan TimeToLiveTimeSpan
+        {
+            get { return timeToLiveTimeSpan; }
+        }
+
+        #endregion
+    }
 }
\ No newline at end of file
diff --git a/test/Spring/Spring.Core.Tests/Caching/BaseCacheAttributeTests.cs b/test/Spring/Spring.Core.Tests/Caching/BaseCacheAttributeTests.cs
index 98302232..20611634 100644
--- a/test/Spring/Spring.Core.Tests/Caching/BaseCacheAttributeTests.cs
+++ b/test/Spring/Spring.Core.Tests/Caching/BaseCacheAttributeTests.cs
@@ -38,6 +38,16 @@ namespace Spring.Caching
 
         private class DerivedCacheAttribute : BaseCacheAttribute
         {
+            public DerivedCacheAttribute()
+            {
+                
+            }
+
+            public DerivedCacheAttribute(string cacheName, string key)
+                : base(cacheName, key)
+            {
+                
+            }
         }
 
         public string TestProperty
@@ -78,7 +88,21 @@ namespace Spring.Caching
         public void AllowsForExtendedTimeSpanConverterSyntax()
         {
             att.TimeToLive = "5ms";
-            Assert.AreEqual( new TimeSpan(0,0,0,0,5), att.TimeToLiveTimeSpan );
+            Assert.AreEqual(new TimeSpan(0, 0, 0, 0, 5), att.TimeToLiveTimeSpan);
+        }
+
+        [Test]
+        [ExpectedException(typeof(ArgumentOutOfRangeException))]
+        public void KeyCannotBeEmptyString()
+        {
+            att = new DerivedCacheAttribute("someName", string.Empty);
+        }
+
+        [Test]
+        [ExpectedException(typeof(ArgumentNullException))]
+        public void KeyCannotBeNull()
+        {
+            att = new DerivedCacheAttribute("someName", null);
         }
     }
 }
\ No newline at end of file