Seven men were almost totally immersed in water at a neutral temperature (34.5 degrees) and given an intravenous injection of exogenous pyrogen. Five subjects who exhibited fever and visible shivering all reported sensations of chill at the time of shivering. Two subjects who did not shiver reported neutral sensation throughout. The results indicate that reduction of skin temperature is not necessary for the chill sensation in fever. The chill must arise from some central action of pyrogen.