The present study aimed at evaluating possible changes of the gluteus maximus muscle bulk size and in the contracting properties of gluteus maximus in the amputated above-knee limb. Seven male above-knee amputees, with a mean age of 47.4 years volunteered to participate in the present study. Twenty-one healthy subjects with a mean age of 34.0 years served as the control group. Muscle belly displacement was measured by means of a precision electromagnetic sensor dc-dc displacement transducer while performing maximal voluntary isometric contractions. The muscle twitch contraction has been quantified by the latency period (T1), time to peak tension (T2) and the slope of the record. A statistically significant decrease in muscle belly displacement on the amputated side has been observed in comparison with controls and non-amputated side. The latency period on the amputated side was significantly longer and the slope less steep than in the control group. These results indicated atrophied and slower gluteus maximus on the amputated side of above-knee amputees.