Abstract: The disclosure is concerned with an axial fan having a casing. Unacceptably high level of noise and low discharge pressure inherent in axial fans are attributable to a counter flow of fluid taking place through the gap between the radially outer ends of the rotating blades and the casing. The invention is directed to preventing the counter flow by providing guide vanes disposed in the gap and inclined symmetrically with the rotating blade, thereby to provide enhanced output flow rate and discharge pressure, as well as to reduce the level of noise. The invention is applicable also to such axial fan as having a baffle plate on the suction side of the rotating blade in the proximity thereof.