In the AfterUpdate event of the combo on the main form requery the list box:
Me.SubformControlName.Form.Requery
Set the criteria of the list box to:
[Forms]![MainFormName]![ComboBoxName]

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Arvin Meyer, MCP, MVP
http://www.datastrat.com
http://www.mvps.org/access
http://www.accessmvp.com
>I have a form with a combo Box in the main form that selects a record
>
[quoted text clipped - 3 lines]
>
> selected with the combo box on the main form