The invention relates to a cylinder (10) of an internal combustion engine, comprising a cylinder liner (11) and a cylinder piston (12) which is guided in the cylinder liner (11). The cylinder piston (12) has multiple ring grooves (18) which are delimited by ring webs (19) and are separated by the ring webs (19). Each of the ring grooves (18) receives a piston ring (20) designed as a compression ring (21) or as an oil scraping ring (22). Each ring groove (20) is delimited by an upper groove flank (23), a lower groove flank (24), and a groove base (25), and each piston ring (20) has a lower ring flank (27) which faces the lower groove flank (24) of the respective ring groove (18), an upper ring flank (26) which faces the upper groove flank (23) of the respective ring groove (18), a ring back (28) which faces the groove base (25) of the respective ring groove (18), and a section (29) which lies opposite the ring back (28) and rests against a radially inner running surface (18) of the cylinder liner (11). A depression (30) is introduced into the lower groove flank (24) of the at least one ring groove (18) or each ring groove which receives a piston ring (20) designed as a compression ring (21) and/or into the lower ring flank (27) of the at least one piston ring (20) or each piston ring designed as a compression ring (21).