After hospital discharge, 114 patients with variant angina were followed for a mean period of 26 months. Six died suddenly and 13 others were resuscitated from sudden cardiac death. The extent of coronary disease and the prevalence of left ventricular dysfunction in these 19 "sudden death" patients were similar to those in the patients who did not experience sudden death ("survivors"). During spontaneous episodes of ST elevation recorded in hospital, 56 of the 114 patients had serious arrhythmias: ventricular fibrillation in two, ventricular tachycardia in 28, ventricular couplets or bigeminy in 17, second- or third-degree atrioventricular block in six and asystole in three. Patients with and those without these arrhythmias during attacks were similar with respect to extent of coronary disease, left ventricular function and most other clinical variables. The maximal ST elevation, however, was higher in the arrhythmia group (7.5 +/- 5.7 vs 3.3 +/- 2.3 mm, p less than 0.01). Serious arrhythmias were detected in 16 of the 19 sudden death patients, compared with 36 of the 86 survivors (p less than 0.01). Sudden death occurred during follow-up in 15 of the 36 patients (42%) with ventricular fibrillation, ventricular tachycardia, high-degree atrioventricular block or asystole during attacks, compared with only four of 69 (6%) without these arrhythmias (p less than 0.001). We conclude that variant angina patients with serious arrhythmias during spontaneous attacks differ from other variant angina patient only in the degree of ischemia during attacks, as reflected by maximal ST elevation, but are at a much higher risk for sudden death.