A randomized trial was performed in 22 patients with unstable angina to compare the efficacy of oral verapamil with nifedipine in reducing symptomatic ischaemic episodes. The trial consisted of a 48 h control period, a 96 h treatment period with nifedipine (20 mg every 6 h) or verapamil (120 mg every 6 h), and a follow-up period. Patients who had a minimum of four symptomatic ischaemic episodes during the control period were entered into the trial. Asymptomatic ischaemic episodes were evaluated by Holter monitoring. Coronary angiography was performed at the end of the treatment period. Both nifedipine and verapamil significantly reduced the mean number of daily symptomatic ischaemic episodes (p less than 0.01) and the total number of ischaemic episodes (p less than 0.03). This study confirmed the high degree of efficacy of both nifedipine and verapamil in reducing the number of ischaemic episodes during short-term treatment of unstable angina. Nevertheless, a significant number of myocardial infarctions occurred in these patients, and some required subsequent coronary bypass graft operations.