Two appetite stimulants, megestrol acetate and cyproheptadine were administered in a randomized trial to 14 patients who had no evidence of opportunistic infection or malabsorption but were wasted (had lost more than 5 kg body weight) as a result of human immunodeficiency virus (HIV) infection. Energy intakes were calculated from a 7 day weighed dietary record. Mean energy intakes per kilogramme body weight were similar in both treatment groups (greater than 34 kcal/kg) and were higher than that in well British males. Energy intakes increased by just over 500 kcal during both treatments, but fell to pretreatment levels after therapy. Patients in both treatment groups gained a moderate amount of weight. Megestrol acetate was associated with impotence in 4 patients. Insufficient calorie intake alone is not a common cause of wasting associated with HIV and the role of appetite stimulants is likely to be limited.