Thermocutaneous, vascular, metabolic and hormonal changes were investigated during 11 hot flashes from 6 postmenopausal women. The first detectable change was an increase in finger blood flow with a concomitant enhancement of skin conductance. The increase in skin conductance was followed rapidly by a sharp rise in finger temperature. The main endocrine-metabolic changes associated with the above phenomena were a sharp increase in plasma free fatty acids (∼65%), norepinephrine (∼ 100%) and LH (∼20%) levels. Plasma glucose and cortisol tended to be increased but did not reach statistical significance; on the other hand, plasma insulin, glucagon, growth hormone, epinephrine and dopamine remained unchanged.