This worked ok for me in xl2003:

Option Explicit
Sub testme()

Dim myCell As Range
Dim myRng As Range
Dim ErrorInMergedCells As Boolean

Set myRng = Selection

ErrorInMergedCells = False
If myRng.Cells.Count = 1 Then
'everything's ok?
ElseIf myRng.MergeCells = False Then
'no merged cells in selection, don't test anything
'true means that the selection consists of merged cells
'null means that the selection has a mixture of
'merged cells and non-merged cells
Else
For Each myCell In myRng.Cells
If myCell.MergeCells Then
If myCell.MergeArea.Columns.Count 1 Then
ErrorInMergedCells = True
MsgBox "You have merged cells across columns " _
& "in the selection." & vbLf & _
"Like: " & myCell.Address & _
" merged across columns " & myCell.MergeArea.Address
Exit For
End If
End If
Next myCell
End If

If ErrorInMergedCells Then
'do nothing
Else
'do the real work??
End If

End Sub

APP OEU wrote:

In my spreadsheet, users are allowed to merge cells in a single
column, but not across rows.

How can I check (in VBA) that the selection contains either a single
cell, or a merged block in a column, and allow the process to
continue, but if the selection contains cells merged across rows, then
present an error message and stop.

Many thanks.

Rick

--

Dave Peterson