This study was investigated the effects of ambient temperatures and menstrual cycle on Resting Metabolic Rate(RMR), Rectal Temperature(Tre), Skin(forehead, chest, abdomen, forearm, hand, thigh, leg, foot) Temperatures, and subjective thermal sensations in 8 young Korean females(ages 22-25, voluntarily). The Tre and the Skin Temperatures were measured in once every five minute for one hour. RMR was measured three times at 30 minutes intervals by indirect calorimetry. All measurements were gathered during Luteal Phase(LP), Menstruation(M), and Follicular Phase(FP) at two levels of ambient temperatures; low(17~21$^{circ}C$) and middle(21.1~$25^{circ}C$). LP were the highest values during FP and M in RMR, Tre, forehead temperature, chest temperature and abdomen temperature, while the leg(leg and foot) and arm(forearm and hand) temperatures were higher during FP rather than during LP at each ambient temperature. The downward curve of Tre in the experiment was larger during FP than LP. The values in subjective thermal sensations were most comfortable during LP than M and FP at each ambient temperature. The LP-FP differences in core and mean skin temperatures, and resting metabolic rate, were more significant at middle ambient temperatures than at low ambient temperatures.