Abstract: A rotary lawn mower blade assembly having replaceable cutting edge members which may be replaced without replacing an entire blade or sharpening the used blade. The cutting edge members slide into place on corresponding “T”-shaped tongues of the blade body until encountering an integral stop. The cutting blade member is securely held in place by a blade retainer having a rectilinear portion which mates with a retainer stud fastened in the blade body and an extension plate portion with mounting cap screws reaching through the blade retainer extension plate into the cutting blade member. In another embodiment the cutting edge members are secured by set screw extending downward from the upper surface of the cutting edge member and bearing against the upper side of the “T”-shaped tongue of the blade body.