This study determines the characteristics of the multiple sclerosis gait, identifies the progressive gait changes associated with this degenerative disease, and determines the effects of an aquatic exercise program on gait parameters. Eleven patients with multiple sclerosis volunteered to participate and were filmed three times during a 10 week period with a Locam camera at 100 frames/s. During the testing period, subjects participated in an aquatic exercise program. In addition, they were rated according to the Kurtzke Scale for Evaluating Disability in Multiple Sclerosis. Results indicated that these patients with MS have shorter stride lengths, slower free speed walking rates, and higher cadence than do persons without MS. Knee and ankle joint rotation were characterized by lower than normal excursion with less vertical lift of the center of gravity and greater trunk lean than normal. Significant correlations between the Kurtzke Scale and gait parameters were indicated for step length and hip and ankle joint excursion. The aquatic exercise program appeared to have had no effect on the studied gait parameters.