Abstract: This invention refers to an oscillating-rotary engine with internal combustion in four strokes and it is made from a block-engine with a single cylinder 1, tightened by to lids 2 and 3, the frontal lid 2 has two orifices 4 and 5 for the inlet and outlet galleries and a spark-plug 6; inside the cylinder, in two bearings 7 and 8 there is an oscillating-rotor unit consisting of a special central hub 9 and two pairs of blades (A-B, C-D), which produces mechanical work under the form of an oscillating rotation; this mechanical work is changed into a continuous rotation by a special gear-group that is placed in case 12; the rotation is transmitted to a shaft-engine 13.