Document.GrammaticalErrors (Word)

Returns a ProofreadingErrors collection that represents the sentences that failed the grammar check in the specified document.

There can be more than one error per sentence. If there are no grammatical errors, the Count property for the ProofreadingErrors collection returned by the GrammaticalErrors property returns 0 (zero). For information about returning a single member of a collection, see Returning an object from a collection.

If ActiveDocument.GrammaticalErrors.Count = 0 Then 
 Msgbox "There are no grammatical errors." 
Else 
 ActiveDocument.CheckGrammar 
End If