An axial flow rotary valve (1) for an internal combustion engine and method of manufacture thereof. The valve comprising a centre portion (5) having a cylindrical periphery, inlet and exhaust portions(9, 16) both smaller in diameter than the centre portion, and an inlet port (3) and an exhaust port (4) terminating respectively as an inlet opening (6) and an exhaust opening (7) in the periphery of the centre portion. The centre portion having at least one elongate passage (21) communicating between the inlet portion and the exhaust portion, the whole of the passage being disposed circumferentially outside the openings and radially outside at least one of the inlet and exhaust portions.