Pedometers are inexpensive and user-friendly devices that might be practical for measuring physical activity among individuals with multiple sclerosis (MS). This study involved an evaluation of the accuracy of two pedometers against actual steps taken under controlled laboratory conditions (five minute bouts of walking at five different treadmill speeds [41, 54, 67, 80, and 94 m x min(-1)]) among 23 individuals with MS who were ambulatory without an aide. Both pedometers exhibited good accuracy with the 67, 80, and 94 m x min(-1) speeds, but poor accuracy with the 41 and 54 m x min(-1) speeds. Those results support the quantification of physical activity using pedometers among those with MS who are ambulatory without an aide.