Six postmenopausal women with hot flashes were studed for two 8-week periods during which they received low-dose danazol (100 mg/24 hours) for one time interval and placebo for the other in a randomized double-blind manner. The patients recorded the number and severity of their hot flashes daily. On the last day of each period the patients were admitted to the research center overnight for an 8-hour monitoring of forehead skin temperatures and for continuous withdrawal of blood to determine 20-minute integrated levels of luteinizing hormone. Three of the six patients responded to danazol with a mean reduction of 88% in the number of hot flashes and a 53% decrease in the severity of hot flashes. Responders differed from nonresponders in that on treatment the frequency of nocturnal pulses of luteinizing hormone was reduced more (36.1% versus 14.4%), the increase in amplitude of the pulses was greater (+30.7% versus -11.8%), and the fall in the mean level of luteinizing hormone was more marked (19.0% versus 10.5%). The findings suggest that danazol may be a reasonable alternative to estrogen in the treatment of postmenopausal women with severe vasomotor symptoms.