The antianginal effect of oral nicorandil was examined on 15 subjects with angina pectoris who had not been improved by previous treatment with beta blocker and/or calcium antagonists. Nicorandil, 5mg tid, was added to their previous regimen which were composed of beta blocker and/or calcium antagonists, and patients were followed up at least for 6 weeks. The following results were obtained; 1) Frequences of anginal attack were markedly reduced in 11(73%) of 15 patients after the use of nicorandil. 2) After the use of nicorandil, ST segment depression and T wave inversions were improved in 10(66.7%) of 15 patients. 3) In 10 patients who had been taken nicorandil over 12 weeks, 9 patients showed sustained improvement in clinical status, but no significant side effect was noted. 4) In two patients who had undergone exercise tolerance test, significant prolongation in exercise duration were noted. 5) The adverse effects of nicorandil were as follows; headache in 3, insomnia in 3, excessive perspiration, dizziness, thirst, constipation and facial fiushing in 1, respectively.