A spark ignition rotary valve internal combustion engine includes a combustion chamber being defined in part by the piston and the combustion end of the cylinder, a valve housing fixed at an outer portion of the combustion end of the cylinder and defining a bore, and a rotary valve rotatable about a rotary valve axis in the bore in the valve housing. The rotary valve has a hollow valve body subjected to combustion gases throughout the combustion process. The rotary valve also has, in a wall part thereof, a port giving, during rotation of the valve, fluid communication successively to and from the combustion chamber via inlet and exhaust ports in the valve housing. The inlet and exhaust ports are angularly offset with respect to a radial line from the center of the engine cylinder.