Abstract: A centrifugal ventilator fan having a base plate with an axis of rotation, an inlet ring having an opening therethrough and a plurality of generally flat blades, each having first and second side edges, a leading edge and a trailing edge is provided. Each blade is connected to the base plate along the first side edge, and is connected to the inlet ring along the second side edge. The blades are radially spaced about the axis of rotation and are backwardly inclined with respect to a direction of rotation of the fan. A portion of each blade adjacent to the leading edge has a radius of curvature such that the blade portion adjacent to the leading edge extends generally inwardly towards the axis of rotation to reduce noise generated by the ventilator fan.