I have three cells (A3, B3 & C3) where I'm using data validation to control
the contents. My worksheet also has a macro button to generate a set of
reports when clicked. I want to update that macro by adding a check for
those three cells to ensure each has been completed, and cancel processing if
they have not.

Can someone provide guidance on setting up the IF statement?

If A3:C3 is blank (not sure how to code this part here)
MsgBox stating cell X or cells XXX are blank and required
Exit Sub
Else
' Do nothing, Ok to continue w/rest of macro
End If

Also, is it better to call a separate macro from my existing macro or just
add the check to the one I already have?

Thanks