The invention relates to an internal combustion piston engine, specially a powerful diesel engine, comprising at least one piston (1) arranged in a cylinder (2), said piston being provided with peripheral grooves (6). Each groove is assigned an open piston ring (3) which is at least partially stressed and located on the cylinder (2). The ends (10, 11) of said ring define a slit (12). Long piston ring service lives can be obtained by providing at least the top piston ring (3) with several grooves (13) on its outer periphery.