FIELD : medicine.SUBSTANCE : invention relates to medical equipment. Surgical circular stapler has a body, a shaft, a stapling assembly, a motor, a cam assembly, and a firing assembly. Shaft extends distally from the body. Stapling assembly is secured to a distal end of the shaft. Longitudinal translation of the firing assembly causes the stapling assembly to drive a plurality of staples in a circular array to secure two lumens of tissue together. Stapling assembly may further drive a blade to sever any excess tissue inside the circular array of staples. Motor is operable to rotate the cam assembly. Rotation of the cam assembly causes longitudinal translation of the firing assembly.EFFECT : single rotation of the cam assembly is operable to drive the firing assembly from a proximal position to a distal position and back to a proximal position.19 cl, 42 dwg