Thirteen patients with Behçet's disease were treated with OP-1206 (oral PGE1) of 15μg together with 50-75 mg of Captopril daily for twenty-four weeks. Incidence of oral aphthous ulcers and nodular erythemas was decresed significantly compared with that estimated in patiets who were given OP-1206 or placebo simply. Blood sedimentation rate and serum C-reactive protein from the patients receiving OP-1206 and Captopril improved steadily, and it was also demonstrated that chemotactic index of neutrophils (PMNs) and proportion of activated T cells were significantly decreased in this patients' group. The treatment did not influence production of oxygen intermediates and phagocytosis of PMNs. Combination of OP-1206 and Capto-pril seems to be a beneficial treatment for the patients with severe mucocoutaneous lesions of Behçet's disease.