We examined the reliability of scores from physical activity monitors in a sample of 193 individuals with multiple sclerosis (MS) who wore a pedometer and an accelerometer for a 7-day period. There were no significant differences among days for the pedometer (p = .12) or the accelerometer (p = .15) indicating that week and weekend days can be analyzed in a single intra-class correlation (ICC) analytic model. The 7 days of monitoring yielded ICC estimates of .93 for both the pedometer and accelerometer, and a minimum of 3 days yielded a reliability of .80 for both the pedometer and accelerometer. Results indicated that physical activity monitor scores are reliable measures of physical activity for individuals with MS.