A prosthesis for maintaining the male penis in an erected disposition during sexual intercourse includes an open ring-like end portion which is receivable in substantially encircling relation on the shaft of a penis adjacent the base of the glans, a pair of support wire elements which extend rearwardly from the end portion along the underside of the penis and along opposite sides of the scrotum to points therebehind, and a retaining ring slidably received on the support wire elements and positionable thereon adjacent the end portion for closing the end portion around the penis. The prosthesis further includes a resilient band element which is securable to at least one of the support wire elements behind the scrotum and postionable so that it extends over the upper side of the penis adjacent to the base thereof for urging the penis forwardly and also slightly upwardly. The preferred form of the prosthesis further includes a stabilizer member which is attached to the support wire elements behind the scrotum and extends rearwardly and upwardly in the posterior crevice between the buttocks for adding further stability to the prosthesis.