This study was supported by the Levine-Rubenstein MS Research Fund and The Rehabilitation Research and Development Service of the U.S. Department of Veterans Affairs. Clinicians might be reluctant to institute exercise training programs for individuals with multiple sclerosis (MS) because so little information is available regarding their muscle performance capability. The purpose of this project was to compare the quadriceps and hamstrings muscle groups' torque capacity of individuals with MS (N = 9) to matched non-MS controls (N = 9). Muscle torques at several speeds were measured using a KIN-COM II isokinetic dynamometer during both concentric (30, 60, and 90 degrees /sec) and eccentric (45, 60, and 75 degrees /sec) contractions. Peak torque for both muscle groups at all velocities were higher for the non-MS group; however, this difference was only significant for the concentric quadriceps muscle contraction (p < .05). All subjects demonstrated higher torque eccentrically than concentrically for the quadriceps, but these differences were only significant for the experimental subjects. The MS group showed a greater decrease in torque with increasing speed than the non-MS group. Deficits between the MS and control groups related to changes in contraction velocity were greater during concentric than eccentric contractions. These findings suggest that strengthening programs that emphasize concentric exercise at the higher of the three speeds of movement included in this study may be most effective in treating this particular type of strength deficit in MS patients. J Orthop Sports Phys Ther 1992;16(3):114-122.