A cylinder head for an internal-combustion engine includes, for each cylinder of the engine, at least one intake duct extending from an inlet located at a lateral face of the head down to an outlet cylindrical mouth and an intake valve associated with each intake duct. The surface of the intake duct has a longitudinal projection for deflecting the flow of air that flows through the intake duct. The projection is configured to provide a deflection of the air flow towards the two sides of the valve stem, so as to substantially reduce the quantity of air that hits the valve stem directly. The projection extends down to the outlet cylindrical mouth, so as to hinder a flow of air through an angular sector of the cross-sectional area of the outlet mouth which angular sector faces towards the lateral face of the cylinder head.