How can I cancel changes made to subform records? I tried Me.Undo in a command button on the main form but it does not work.

Any help will be appreciated.

Thanks.

Once focus has left each subform record, it has already been saved. See the following two articles for more detailed explainations and suggestions:

ACC: Main Form Record Edits Saved When Subform Gets Focus (Q132033) http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q132033

ACC: Unable to Undo or Rollback Main Form and Subform Changes (Q131535) http://support.microsoft.com/default.aspx?scid=kb;en-us;Q131535

These articles ultimately lead you to a sample contained in frmsmp97.mdb. The sample uses temp tables to store the "old" values so they can be restored if necessary.