The aim of this study was to evaluate a low-dose regimen of megestrol acetate (MA; 320 mg/day) on appetite in advanced cancer patients. Out-patients with far-advanced non-hormone responsive tumours and loss of appetite were randomised in a phase III trial, with two consecutive phases: a 14-day double-blind placebo controlled phase (phase A) and a 76-day open phase (phase B). During phase A, patients were treated with MA, two 160 mg tablets/day, or placebo. In phase B, the MA dose was titrated to clinical response in both groups. Appetite, food intake, body weight, performance status, mood and quality of life were evaluated with standardised measures; patients' global judgement about treatment efficacy was also requested. Of 42 patients entering the study, 33 (17 MA and 16 placebo) were evaluable for efficacy. The appetite score improved significantly with MA after 7 days (P = 0.0023), and this effect was still significant at 14 days (P = 0.0064). Patients judged the treatment with MA effective in 88.2% of cases (14th day), whilst placebo was considered effective by 25% (P = 0.0003). None of the other measures showed significant changes during treatment. The remarkable effect on appetite evident after 7 days, without serious side-effects, shows that MA can produce significant subjective effects at a low-dose even in patients with far-advanced disease.