BACKGROUND. Mepartricin, a semisynthetic polyene derivative with a favorable effect on urethro-prostatic function, was clinically evaluated, adopting the diagnostic and research criteria recommended by the First International Consultation on BPH. METHODS. A multicenter, randomized, double-blind, parallel-group study compared mepartricin 40 mg/daily to placebo in the treatment of 196 patients with newly diagnosed BPH and mild-to-moderate symptomatology. International Prostate Symptom Score (I-PSS), quality of life (QoL) index and maximum urinary flow-rate (Q max ) were determined every 4 weeks for 6 months; postvoiding volume, prostate volume, and prostate-specific antigen (PSA) were assessed after 3 and 6 months of therapy. RESULTS. Mepartricin was shown to determine a statistically significant improvement over placebo in I-PSS and QoL index from month 2 onwards, and a significant linear increase in Q max over the study period. At month 6, the improvement in the mepartricin and placebo groups in I-PSS, QoL index, and Q max was 6.3 (standard error (SE) 0.51) and 4.2 (SE 0.60) points (P = 0.003), 0.99 (SE 0.14) and 0.62 (SE 0.12) points (P = 0.036), and 2.7 (SE 0.46) and 1.2 (SE 0.46) ml/sec (P = 0.051), respectively. No significant differences were noted in postvoiding residual volume, prostate volume, or PSA. Mepartricin tolerability was good, showing no adverse events on sexual function. CONCLUSIONS. Mepartricin proved to be an effective treatment of benign prostatic hyperplasia, determining an improvement in symptoms, quality of life, and peak urinary flow.