The latest lower-limb prosthetic designs have been incorporated with dynamic elastic response (DER) components to enhance prosthesis flexibility, which are suggested to be beneficial to gait. Although DER prosthetic. feet are preferred by most transtibial amputees and their benefits to gait are supported by some biomechanical studies, many are still utilizing the simple conventional solid ankle cushioned heel (SACH) designs because of the lower cost. The monolimb, a transtibial prosthesis with the socket and the shank molded from a single piece of thermoplastic material, perhaps is an alternative to DER feet for providing flexibility at the shank. In addition to shank flexibility, low cost and light weight are other characteristics of monolimbs. In spite of the potential benefits, little analysis has been done to examine the simple-structured monolimb prosthesis. The main aim of this study is to evaluate the gait and perception of unilateral transtibial amputees using a flexible elliptical-shank monolimb as compared to a thicker circular-shank monolimb and a conventional rigid-shank prosthesis. Results suggested that a properly designed monolimb may potentially offer similar functional advantages to the relatively expensive DER feet.