Abstract: An axial-flow fan having a stepped housing defined by an inlet part and an outlet part, the outlet part having the inside diameter smaller than the inside diameter of the inlet part, the inlet part adjoined to an inlet tube of an inside diameter substantially equal to the inside diameter of the outlet part of the housing. The outlet part of the housing accommodates a rotor having blades arranged such that their forward tips are located in the inlet part of the housing and a ferrule being secured at a certain distance from the inlet tube coaxially with the housing to form with the housing an annular chamber having on the side of the rotor an inlet passage and on the side of the inlet tube an outlet passage. Rigidly affixed in this chamber are guide vanes pointing by their heels to the inlet tube. The heels of the guide vanes extend to the inlet tube and are radially curved at a portion between the inlet tube and the ferrule to form an annular radial grill.