The present invention relates to a piston (10) for an internal combustion engine, comprising a piston head (11) and a piston skirt (16), wherein the piston head (11) has a circumferential ring part (15) and a circumferential cooling channel (23) in the region of the ring part (15), wherein the piston skirt (16) has piston bosses (17), which are provided with boss bores (18) and which are arranged on the underside (11a) of the piston head (11) by means of boss connections (19), wherein the piston bosses (17) are connected to each other by means of running surfaces (21, 22). According to the invention, at least one axial bore (24a, 24b, 24c, 24d), which is closed to the outside and which is arranged between a running surface (21, 22) and a boss bore (18), is provided inside a piston boss (17), the at least one bore (24a, 24b, 24c, 24d) opens into the cooling channel (23), and the cooling channel (23) and the at least one bore (24a, 24b, 24c, 24d) contain a filling (27) of sodium and/or potassium.