Hallo,

hier nun angepasst:

Option Explicit

Public Sub sort_groups()
    Dim l As Long, z As Long
    Dim iColGrp As Integer, iColSort As Integer, iColOut As Integer, tmp As Integer
    Dim wks As Worksheet
       
    l = 2                               'Zeile, in der begonnen wird, bei Tabellen mit Überschrift = 2
    iColGrp = 1                         'Spalte, in der die Gruppe steht (Ganzzahliger Wert)
    iColSort = 2                        'Spalte, in der das Sortierkriterium steht (Ganzzahliger Wert)
    Set wks = Worksheets("Tabelle1")    'Tabelle, die bearbeitet werden soll
       
    With wks
        Do While .Cells(l, iColGrp) <> vbNullString And .Cells(l, iColSort) <> vbNullString
            tmp = CInt(.Cells(l, iColSort))
            z = l
            Do While .Cells(l, iColGrp) = .Cells(z, iColGrp)
                If .Cells(l, iColSort) > tmp Then
                    tmp = .Cells(l, iColSort)
                End If
                l = l + 1
            Loop
            Call mark_max_group_sort(wks, iColGrp, iColSort, .Cells(z, iColGrp), tmp)
        Loop
    End With
      
    Set wks = Nothing
End Sub
   
Private Sub mark_max_group_sort(ByRef wks As Worksheet, ByVal iColGrp As Integer, ByVal iColSort As Integer, ByVal sGrp As String, ByVal sSort As String)
    Dim tmp As String
    Dim l As Long
    l = 1
       
    With wks
        Do While .Cells(l, iColGrp) <> vbNullString And .Cells(l, iColSort) <> vbNullString
            tmp = CStr(.Cells(l, iColGrp) & .Cells(l, iColSort))
            If tmp = CStr(sGrp & sSort) Then
                .Cells(l, iColSort).Interior.Color = RGB(255, 0, 0)
            End If
            l = l + 1
        Loop
    End With
End Sub

Gruß