http://msmvps.com/blogs/paulomorgado/archive/2008/05/30/getting-net-1-1-clr-string-hash-codes-in-the-net-2-0-clr.aspxEveryone knows (or, should know) that values values retrieved from the GetHashCode method should not be persisted for later use, specially with strings , because: The behavior of GetHashCode is dependent on its implementation, which might change fromenCommunityServer 2008.5 SP2 (Build: 40407.4157)