Disclosed is a shaft seal which is suitable especially for vacuum pumps such as propeller pumps. Said shaft seal comprises an inner sealing ring (18) that can be connected to the shaft, and an outer sealing ring (20) which surrounds the inner sealing ring (18). A circumferential groove (30) into which buffer gas can be introduced via a feeding duct (22) is provided in the outer sealing ring (20). A buffer gas disk (34) that is fitted with an attachment (32) which extends into the groove (30) can also be connected to the shaft (10), whereby a buffer gas chamber (28) is embodied in the groove (30). Said buffer gas chamber (28) is joined to a sealing gap (40) located between the inner and the outer sealing ring (18, 20) via a chamber gap (36) which the buffer gas can penetrate. A separation chamber (42) which is formed by the inner and the outer sealing ring (18, 20) and is connected to a discharge duct (44) in order to evacuate buffer gas adjoins the sealing gap (40).
