The relative weight (W(r)) index of body condition provided insight into the stock dynamics of walleye Stizostedion vitreum in six reservoirs in the North Platte River drainage of Wyoming. The three most upstream reservoirs are managed as both walleye and trout (Oncorhynchus spp. and Salmo spp.) fisheries; trout are stocked annually. The three downstream reservoirs are managed for coolwater and warmwater fishes, and walleye fry are stocked almost annually in two of the reservoirs. Positive relations between stocking densities of trout and W(r) of walleyes and between water levels and W(r) of walleyes were observed. Length-related trends in W(r) within walleye stocks over time were related to prey availability.