The efficacy and safety of the Russian phosphodiesterase type 5 inhibitor sildenafil-C3 in combination with a natural complex of the Russian multicomponent dietary supplement (DS) Erectogenon were investigated in 75 patients with erectile dysfunction (ED) and benign prostatic hyperplasia (BPH). Clinical and Doppler ultrasound examinations revealed moderate ED in 34 study group patients who had received combined treatment with sildenafil and the DS Erectogenon for 4 weeks. In the same perod, 21 patients from a comparative group (Group 2) had taken sildenafil only and 20 patients from a comparative group (Group 3) had used the natural biocomplex DS Erectogenon only. The investigation revealed mild ED in the patients from Groups 2 and 3. The immediate and late treatment results were assessed 4 and 12 weeks after the end of treatment, respectively. Combined therapy with sildenafil + Erectogenon was found to statistically significantly enhance its efficiency and to improve quality of sexual life in 85.3 % of the study group patients who had moderate ED. This patient group had a more marked positive clinical effect (a mean increase in erection quality by 7.0 scores by the International Index of Erectile Function, a rise in penile blood flow by 3.5 times, and a reduction in the International Prostatitis Symptom Index by 5 scores). Sildenafiil-C3 or Erectogenon monotherapy provided a lower effect in the comparative groups. The findings confirm that combined therapy with the Russian drugs sildenafil-C3 and DS Erectogenon is effective, safe, and well-compatible and causes no adverse reactions and the synergism of the components of the biocomplex DS Erectogenon prolongs the effect of daily low-dose sildenafil. The combined treatment may be recommended for the treatment of ED in patients with BPH, for this affects the pathogenesis of the disease, alleviates the progression of ED, and improves their quality of life. The treatment should be used in moderate ED and moderate reductions in urodynamic symptoms, by keeping in mind penile and prostatic Doppler ultrasound findings.