The authors assessed the validity of a treatment with mepartricin in BPH at the dose of 150,000 U in a once-a-day evening administration for 6 months. The results from the controlled study were compared with those obtained in a homogeneous group of patients treated with placebo. The analysis of the data obtained would suggest a preferential opinion in favour of the group treated with mepartricin which was effective in improving the symptomatology. Some hypothesis are put forward to interpret the results.