A centrifugal exhaust fan for bathrooms, comprising: an outer casing with a front part, a rear part determining a seating plane for the exhaust fan and a tubular nozzle extending rearwards from said seating plane for coupling to an air outlet tube; an inner casing; a drive motor; and a rotating drum located transversely in front of a rear air outlet port of the inner casing and coupled to the drive motor; and wherein the inner casing is housed partially inside the tubular nozzle, the rotating drum being set back partially rearwards with respect to the seating plane of the exhaust fan; and whereby: the drive motor is arranged within the rotating drum; a clearance (h), greater than 0.16 times but smaller than 0.30 times a diameter of the tubular nozzle, is provided between the inner casing and the outer casing, so that an air passage is defined from an intake of the front part of the outer casing to side openings of the inner casing, located opposite the ends of the rotating drum; and the inner casing comprises outwardly extending flanges behind the side openings, closing the gap between the inner and outer casings (2,3) to prevent air flow, within the exhaust fan, between a negative pressure area where the side openings are located and a pressure area located behind the rotating drum. an outer casing with a front part, a rear part determining a seating plane for the exhaust fan and a tubular nozzle extending rearwards from said seating plane for coupling to an air outlet tube; an inner casing; a drive motor; and a rotating drum located transversely in front of a rear air outlet port of the inner casing and coupled to the drive motor; and wherein the inner casing is housed partially inside the tubular nozzle, the rotating drum being set back partially rearwards with respect to the seating plane of the exhaust fan; and whereby: the drive motor is arranged within the rotating drum; a clearance (h), greater than 0.16 times but smaller than 0.30 times a diameter of the tubular nozzle, is provided between the inner casing and the outer casing, so that an air passage is defined from an intake of the front part of the outer casing to side openings of the inner casing, located opposite the ends of the rotating drum; and the inner casing comprises outwardly extending flanges behind the side openings, closing the gap between the inner and outer casings (2,3) to prevent air flow, within the exhaust fan, between a negative pressure area where the side openings are located and a pressure area located behind the rotating drum. the drive motor is arranged within the rotating drum; a clearance (h), greater than 0.16 times but smaller than 0.30 times a diameter of the tubular nozzle, is provided between the inner casing and the outer casing, so that an air passage is defined from an intake of the front part of the outer casing to side openings of the inner casing, located opposite the ends of the rotating drum; and the inner casing comprises outwardly extending flanges behind the side openings, closing the gap between the inner and outer casings (2,3) to prevent air flow, within the exhaust fan, between a negative pressure area where the side openings are located and a pressure area located behind the rotating drum.