Hi Jonas,
one method:

Sub LinesInCell()
Dim z1 As Integer
Dim z2 As Integer
With Selection
  .Cells(1).Select
  z1 = .Information(wdFirstCharacterLineNumber)
  .EndKey
  z2 = .Information(wdFirstCharacterLineNumber)
End With
  MsgBox z2 - z1 + 1
End Sub

But not reliable anymore, as in Word 2002
unlike in Word 97 all too often
.Information(wdFirstCharacterLineNumber) returns -1,
and as this does not provide for cells reaching over
page breaks.

Another method:

Sub LinesInCell_1()
Dim r As Long
Dim l As Long
With Selection
   .Cells(1).Select
   .Collapse
   l = 0
   r = .Cells(1).RowIndex
   On Error Resume Next
   Do Until r <> .Cells(1).RowIndex
     If Err.Number = 5941 Then
        Err.Clear
        Exit Do
     End If
     l = l + 1
     .MoveDown
   Loop
   .MoveUp ' or better restore original selection
End With
MsgBox l
End Sub

Counts lines even if the cell spans over several pages.
You might add some lines to get the selection back
to where it was before doing the counting.
And better rewrite it to a function.

Greetings from Bavaria, Germany
Helmut Weber, MVP
"red.sys" & chr(64) & "t-online.de"
Word 2002, Windows 2000