The effects of single evening doses of alpha-methyldopa and placebo have been compared in 40 women with climacteric hot flushes. The study was designed as a double-blind, randomized and cross-over investigation. Of the 24 patients who completed the study, 15 reported that they preferred the alpha-methyldopa treatment (p greater than 0.05). alpha-methyldopa seemed to affect both the severity (p less than 0.05) and the frequency of climacteric hot flushes (p greater than 0.05). It is concluded that alpha-methyldopa is efficacious against climacteric hot flushes when given as single evening doses, but further study is required to answer whether this dosage is as effective as a twice daily regimen.