1. Experiments were performed to study the interaction of skin and core temperatures in the control of heat production. Shorn goats with intravascular heat exchangers to control core temperature were immersed to the neck in a circulating water bath to clamp skin temperature. With bath temperature kept constant at levels between 32 and 42 degrees C, core temperature was varied between 40 and 36 degrees C, and the changes in heat production were measured. 2. With falling core temperature shivering occurred at all bath temperatures, and heat production rose. The threshold of core temperature below which heat production increased varied inversely to the level of skin temperature. Even at a bath temperature of 42 degrees C the slope at which heat production rose exceeded -5 W. kg-1 . C-1. The results show that in the goat even very high skin temperatures do not abolish the central impulse to shiver which is caused by low core temperature. 3. It is concluded that in the control of heat production, skin temperature and core temperature provide linear and independent inputs which do not replicate any known relationship between temperature and discharge frequency of thermoreceptors.