diff --git a/source/java/org/alfresco/repo/content/MimetypeMap.java b/source/java/org/alfresco/repo/content/MimetypeMap.java
index 818f904ae9..89594ab2a1 100644
--- a/source/java/org/alfresco/repo/content/MimetypeMap.java
+++ b/source/java/org/alfresco/repo/content/MimetypeMap.java
@@ -26,16 +26,16 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
-import org.springframework.extensions.config.Config;
-import org.springframework.extensions.config.ConfigElement;
-import org.springframework.extensions.config.ConfigLookupContext;
-import org.springframework.extensions.config.ConfigService;
 import org.alfresco.error.AlfrescoRuntimeException;
 import org.alfresco.repo.content.encoding.ContentCharsetFinder;
 import org.alfresco.service.cmr.repository.MimetypeService;
 import org.alfresco.util.PropertyCheck;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.springframework.extensions.config.Config;
+import org.springframework.extensions.config.ConfigElement;
+import org.springframework.extensions.config.ConfigLookupContext;
+import org.springframework.extensions.config.ConfigService;
 
 /**
  * Provides a bidirectional mapping between well-known mimetypes and
@@ -295,14 +295,27 @@ public class MimetypeMap implements MimetypeService
     public String getExtension(String mimetype)
     {
         String extension = extensionsByMimetype.get(mimetype);
-        if (extension == null)
+        return (extension == null ? EXTENSION_BINARY : extension);
+    }
+    
+    /**
+     * Get the mimetype for the specified extension
+     * 
+     * @param extension a valid file extension
+     * @return Returns a valid mimetype if found, or {@link #MIMETYPE_BINARY binary} as default.
+     */
+    public String getMimetype(String extension)
+    {
+        String mimetype = MIMETYPE_BINARY;
+        if (extension != null)
         {
-            return EXTENSION_BINARY;
-        }
-        else
-        {
-            return extension;
+            extension = extension.toLowerCase();
+            if (mimetypesByExtension.containsKey(extension))
+            {
+                mimetype = mimetypesByExtension.get(extension);
+            }
         }
+        return mimetype;
     }
 
     public Map<String, String> getDisplaysByExtension()
@@ -340,13 +353,12 @@ public class MimetypeMap implements MimetypeService
      */
     public String guessMimetype(String filename)
     {
-        filename = filename.toLowerCase();
         String mimetype = MIMETYPE_BINARY;
         // extract the extension
         int index = filename.lastIndexOf('.');
         if (index > -1 && (index < filename.length() - 1))
         {
-            String extension = filename.substring(index + 1);
+            String extension = filename.substring(index + 1).toLowerCase();
             if (mimetypesByExtension.containsKey(extension))
             {
                 mimetype = mimetypesByExtension.get(extension);
diff --git a/source/java/org/alfresco/repo/content/MimetypeMapTest.java b/source/java/org/alfresco/repo/content/MimetypeMapTest.java
index ad39600ba9..460becc5c4 100644
--- a/source/java/org/alfresco/repo/content/MimetypeMapTest.java
+++ b/source/java/org/alfresco/repo/content/MimetypeMapTest.java
@@ -80,4 +80,23 @@ public class MimetypeMapTest extends TestCase
         assertNotNull("No charset finder", mimetypeService.getContentCharsetFinder());
     }
 
+    public void testMimetypeFromExtension() throws Exception
+    {
+        // test known mimetype
+        assertEquals("application/msword", mimetypeService.getMimetype("doc"));
+        // test case insensitivity
+        assertEquals("application/msword", mimetypeService.getMimetype("DOC"));
+        
+        // test fallback for unknown and missing
+        assertEquals(MimetypeMap.MIMETYPE_BINARY, mimetypeService.getMimetype(null));
+        assertEquals(MimetypeMap.MIMETYPE_BINARY, mimetypeService.getMimetype("unknownext"));
+    }
+    
+    public void testGuessMimetypeForFilename() throws Exception
+    {
+        assertEquals("application/msword", mimetypeService.guessMimetype("something.doc"));
+        assertEquals("application/msword", mimetypeService.guessMimetype("SOMETHING.DOC"));
+        assertEquals(MimetypeMap.MIMETYPE_BINARY, mimetypeService.guessMimetype("noextension"));
+        assertEquals(MimetypeMap.MIMETYPE_BINARY, mimetypeService.guessMimetype("file.unknownext"));
+    }
 }
diff --git a/source/java/org/alfresco/service/cmr/repository/MimetypeService.java b/source/java/org/alfresco/service/cmr/repository/MimetypeService.java
index a700d1da8a..fdeee160a5 100644
--- a/source/java/org/alfresco/service/cmr/repository/MimetypeService.java
+++ b/source/java/org/alfresco/service/cmr/repository/MimetypeService.java
@@ -31,7 +31,6 @@ import org.alfresco.service.PublicService;
  * This service interface provides support for Mimetypes.
  * 
  * @author Derek Hulley
- *
  */
 @PublicService
 public interface MimetypeService
@@ -41,11 +40,19 @@ public interface MimetypeService
      * 
      * @param mimetype a valid mimetype
      * @return Returns the default extension for the mimetype
-     * @throws AlfrescoRuntimeException if the mimetype doesn't exist
      */
     @NotAuditable
     public String getExtension(String mimetype);
 
+    /**
+     * Get the mimetype for the specified extension
+     * 
+     * @param extension a valid file extension
+     * @return Returns a valid mimetype if found, or null if does not exist
+     */
+    @NotAuditable
+    public String getMimetype(String extension);
+
     /**
      * Get all human readable mimetype descriptions indexed by mimetype extension
      *