An experimental investigation was conducted to ascertain the effect of leading-edge bluntness on the laminar boundary layer of a flat plate. The results show that the effect of leading-edge bluntness is an important consideration. The ratio of the leading-edge thickness to theoretical values** of boundary layer displacement thickness at the measuring station will serve as a criterion of the importance of the effect. I t is concluded that the presence of a detached shock wave at the plate leading edge is responsible for the observed discrepancy between theoretically predicted and measured momentum losses. I t is demonstrated that blunting the point of a body of revolution does not seriously affect the laminar boundary layer.