This disclosure deals with a reciprocating piston for an internal combustion engine, particularly for a diesel engine. The piston is made of a relatively high strength metal such as iron, and no more material is used than is necessary to withstand the thermal and mechanical loads encountered in use. A circular piston dome is supported by a support part which extends between the dome and a pair of piston pin bosses. The bosses also support arcuate side thrust pads. A ring band is connected to the outer periphery of the dome by a connecting part which is relatively thin and flexible. The dome, the ring band and the support part are generally symmetrical about the axis of the piston. The support part is annular in cross section and may be conical, cylindrical, or partly conical and partly cylindrical.