To study the temporal relationship of occlusion and reperfusion we examined 16 patients (14 m, 2f) with variant angina for the occurrence and time course of arrhythmias with episodes of ST-elevation (n = 82). The patients underwent frequency-modulated ambulatory ECG recording, episodes of ST elevation were defined, and the arrhythmias were counted before, during and after each episode. In 10 patients (group A) no or only infrequent extrasystoles occurred. Of the other 6 patients (group B), one had a-v block II degree, 5 had frequent (greater than 2/min) ventricular or supraventricular premature beats, 3 with couplets or runs of VPB. Patients of group A and B did not differ in age, severity of fixed coronary stenoses and ventricular ejection fraction. There was a tendency towards a greater incidence of higher ST-elevations (greater than 2 mm) in group B (4 of 6 patients versus 2 of 10 in group A, p = 0.09). The relationship of arrhythmias and ST changes showed different patterns: the maximum of arrhythmias occurred during the episode in 3 patients, during and after the episode in 2 patients and only after the episode in 1 patient. Potentially dangerous arrhythmias are frequent in patients with variant angina and persist beyond the ST segment changes in one half of the affected patients.