Forty-four patients with erectile dysfunction (ED) aged 21-72 years aged 21-72 years (mean age 61 years) were examined and treated with sildenafil and alprostadil monotherapy or combined therapy. ED was psychogenic in 9(20.5%), arterial in 12(27.2%), vein occlusive in 9(20.5%) and neurogenic in 14(31.8%) patients. Monotherapy was most effective in psychogenic ED (alprostadil--100%, sildenafil--88.9%), least effective in vein occlusive ED (alprostadil--33.3%, sildenafil--22.2%). Alprostadil was more effective in arterial and neurogenic ED (83.3 vs 66.7 and 78.6 vs 57.1%, respectively). Combination of the two drugs produced much high response: 100, 85.7 and 55.5% in arterial, neurogenic and vein occlusive ED, respectively. Thus, combined treatment with sildenafil and alprostadil is a method of choice in the treatment of ED in failure of monotherapy with these drugs or in vein occlusive ED. In the combined treatment dose of the drugs, number of side effects and cost of therapy are lower.