Diel movement of muskrats (Ondatra zibethicus) in a Louisiana brackish, coastal marsh was determined using 37 radio-collared muskrats and a total of 2,046 radio fixes during a 13-month period. Monthly home range averaged 0.48 ha but varied considerably among animals; no differences in home ranges were detected among seasons or sex-age classes of muskrats. Also, no differences in hourly movements were found among sex-age classes during periods of day. During winter and spring, differences were detected among individual muskrats. Comparison of seasonal means for all times of day and for all sex-age classes revealed that hourly movement rates were greater in spring than in summer or winter, but did not differ from fall movements. Fall movements did not differ from summer or winter movements. Temperature and marsh water depth had a minor effect on distances moved; neither factor explained more than 21% of the variation in distances moved.