Option Explicit
Sub Macro1()

    'Written by Trebor76
    'Visit my website www.excelguru.net.au

    Dim lngMyRow As Long
    Dim lngLastRow As Long
    Dim rngMyRange As Range

    lngLastRow = Cells(Rows.Count, "A").End(xlUp).Row

    For lngMyRow = 201 To lngLastRow Step 201

        If lngMyRow <> 201 Then lngMyRow = lngMyRow - 1

        If rngMyRange Is Nothing Then
            Set rngMyRange = Cells(lngMyRow, "A")
        Else
            Set rngMyRange = Union(rngMyRange, Cells(lngMyRow, "A"))
        End If

    Next lngMyRow

    rngMyRange.EntireRow.Insert

    Application.ScreenUpdating = True

    MsgBox "Rows have now been inserted"

End Sub