A hydraulic camshaft-adjusting device of the rotary piston type having a drive gear (2) and an impeller. The drive gear (2) has a cavity formed from a perimeter wall and two side walls (5, 6) inside of which at least one hydraulic working chamber is formed from at least two boundary walls (8). The impeller has a wheel hub (10) with at least one vane that extends into a working chamber, dividing the chamber into two associated hydraulic pressure chambers. The pressure medium feed to and from the pressure chambers is done using a pressure medium tap (16) on the side facing a camshaft as well as using pressure medium channels (17) incorporated into the axial sides (14, 15) of the wheel hub (10) of the impeller, which are connected to the pressure medium tap through a pressure medium distributor (20). The pressure medium tap (16) and the pressure medium distributor (20) are encircled at the head (19) and the outer surface (21) by a respective penetration (22, 23) in the side walls (5, 6) of the drive gear (2). The gaps between the head (19) of the pressure medium distributor (20) at the penetration (22) of the one side wall (5) of the drive gear (2) and between the outer surface (21) of the pressure medium tap (16) and the penetration (23) at the other side wall (6) of the drive gear (2) are sealed off through wear-resistant sealing media against pressure medium leakage