If I remember correctly, truncating a table generally resets the identity value back to the start. If that happened, you would probably not notice this as a problem. More likely someone has used IDENTITY_INSERT to manually enter values for your identity column. You should be able to use DBCC CHECKIDENT(tablename) to reset the identity value, but test on a test machine first, as I do not have a Sybase manual handy to check that with.