Abstract: A ventilator for farm barns which is constructed to be positioned over an elongated opening along the ridge of the barn roof. The ventilator is comprised of sheet metal and has inner baffle and flue portions and an outer storm band casing which is about twice as wide as it is high. The baffle portion is in the form of an isosceles triangle the side walls of which extend laterally beyond the width of the flue portion. Rows of louvers in the base of the baffle portion and in the side walls of the flue portion open downwardly and outwardly while those in the base of the baffle portion are directed inwardly. The top of the storm band has louvers therein opening toward the ridge line. The structure provides a simple, effective, weatherproof ventilator.