Abstract: An air distribution unit for mounting in the wall or floor of a room having a plenum space behind the wall or floor, comprises a housing having an air inlet for communication with the plenum space and an air outlet; a blower between the air inlet and air outlet for drawing air from the plenum space and exhausting it through the air outlet into the room; and a grill assembly mounted over the air outlet. The grill assembly has aerodynamically profiled air distribution channels which may be circumferentially disposed, extending between the upper and lower surfaces thereof. The air distribution channels open out onto the upper surface of the grill assembly at a shallow angle in a radially outward direction so that air flowing out of said channels is directed outwardly at an angle of between about 15.degree. and 45.degree. to the plane of the grill assembly.