Try:
Code:
Sub ModifyActiveTable()
Dim i As Long
With Selection
If .Information(wdWithInTable) = False Then Exit Sub
With .Tables(1)
'Kill any existing borders
.Borders(wdBorderTop).LineStyle = wdLineStyleNone
.Borders(wdBorderLeft).LineStyle = wdLineStyleNone
.Borders(wdBorderBottom).LineStyle = wdLineStyleNone
.Borders(wdBorderRight).LineStyle = wdLineStyleNone
.Borders(wdBorderHorizontal).LineStyle = wdLineStyleNone
.Borders(wdBorderVertical).LineStyle = wdLineStyleNone
For i = 1 To .Rows.Count
'Restore borders to every 2nd row
If i Mod 2 = 0 Then
With .Rows(i).Cells
.Borders(wdBorderTop).LineStyle = wdLineStyleSingle
.Borders(wdBorderLeft).LineStyle = wdLineStyleSingle
.Borders(wdBorderBottom).LineStyle = wdLineStyleSingle
.Borders(wdBorderRight).LineStyle = wdLineStyleSingle
.Borders(wdBorderHorizontal).LineStyle = wdLineStyleSingle
.Borders(wdBorderVertical).LineStyle = wdLineStyleSingle
End With
End If
Next
End With
End With
End Sub