The study aimed at comparing an effectiveness of drugs increasing local blood flow injected into cavernous bodies of penis in the treatment of erective impotence in diabetic patients. Fifteen diabetic patients aged between 33 and 60 years with impotence lasting for 4 years have been selected. Patients have been treated with papaverine HCl in the dose of 20-40 mg, papaverine HCl in the same dose combined with phentolamine 5 mg, and prostaglandin E1 in the dose of 20 micrograms. Each patient has been all tested drugs. The most favourable results, i.e. most effective and without adverse reactions (priapism), have been produced by prostaglandin E1 which seems a drug of choice in the treatment of erective impotence in patients with long-lasting diabetes mellitus.