To study scrotal thermoregulation and its efficacy to work against heat accumulation, five subjects were exposed to four experimental conditions under which core and skin temperatures and sweat evaporative responses of various skin surfaces--chest, abdomen and scrotum--were compared. The temperature response of the scrotal area exhibited the largest inertia, and this observation is likely to be the consequence of heat exchange via the vascularization of testes and scrotum which is more efficient than in other parts of the body in limiting local heat storage, thus alleviating heat stress of the testis. The pulsatile nature and the synchronous pattern of the scrotal evaporative heat loss indicate that scrotal sweating takes place, although the gradient response appeared to be less marked than elsewhere in the body. Relatively low and inert scrotal temperature can partly explain this poor local drive for sweating.