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 (D) 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 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 (D) 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 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 (D) 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 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 . <EOS>