Assumes your data starts at row 1.
Change the limits of r to suit your requirement. Note that, as the code adds
a blank line after each X, this row range will have to be at least double
the original row range.
Note that X is case specific.

Sub test()
' Lower value for r should be first data row + 1
' Upper value = lower value + number of original rows
For r = 2 To 20
' X is case specific
If Cells(r - 1, 1).Value = "X" Then
Cells(r, 1).EntireRow.Insert
End If
Next
End Sub

Ian
wrote in message
...
I have a problem. How to insert a row below a cell that contains a
given sign? For example, I need to insert a new row below every cell
that contains x? X is in in every row in column A.