Objective: To determine the effect of a cold bath (24°C) on oxygen consumption and perceived exertion during ambulation and on spasticity in individuals with mild to moderate multiple sclerosis. Design: A repeated- measures design with random assignment of experimental and control conditions. Setting: Outpatient physical therapy department associated with an academic institution. Patients: Fourteen individuals with clinically definite multiple sclerosis exhibiting spasticity and capable of ambulating at 0.7m/sec on a motorized treadmill without handrail support. Measurement: Assessment of oxygen uptake, heart rate, and perceived exertion occurred during two 10-minute walks interspersed with a 30-minute rest on 2 separate days. Measurement of spasticity occurred three times during each session. Results: Oxygen consumption and perceived exertion were unchanged. Spasticity was higher immediately (p < .05) after the cold bath. Conclusions: Increase in spasticity was statistically significant, but unlikely to be of any clinical importance. Contrary to our hypothesis, a cold bath (24°C) for 20 minutes did not reduce oxygen consumption or rating of perceived exertion during ambulation.