Public Function ListeVerzeichnis(Pfad As String, Dateiendung As String) As _
  String()
    Dim FSO As FileSystemObject
    Set FSO = New FileSystemObject
    ReDim ListeVerzeichnis(0)
    Dim Verz As Folder
    Set Verz = FSO.GetFolder(Pfad)
    Unterordner Verz, vbNullString, ListeVerzeichnis, Dateiendung, FSO
End Function
 
Private Sub Unterordner(Ordner As Folder, BisherigerPfad As String, ListArr() _
  As String, Endung As String, FSO As FileSystemObject)
    Dim Datei As File, Subordner As Folder
    For Each Subordner In Ordner.SubFolders
        Unterordner Subordner, BisherigerPfad & IIf(BisherigerPfad = "", "", _
          "\") & Ordner.Name, ListArr, Endung, FSO
    Next
    For Each Datei In Ordner.Files
        If Endung = ".*" Or LCase(Right(Datei.Name, Len(Endung))) = LCase( _
          Endung) Then
            ReDim Preserve ListArr(UBound(ListArr) + 1)
            ListArr(UBound(ListArr)) = BisherigerPfad & IIf(BisherigerPfad = _
              "", "", "\") & Datei.Name
        End If
    Next
End Sub