How many movies have Hans Steinhoff and Rudolf Klein-Rogge collaborated on?

They have worked on 4 movies together! Their first movie together was Die Sandgräfin (1928) while their highest rated movie together was Robert Koch, der Bekämpfer des Todes (1939). They have not worked together since Robert Koch, der Bekämpfer des Todes (1939). They are most known for their drama films together.