During the years 1971-1974, ambulatory ECG monitoring (AEM) during everyday activities was done in 888 consecutive subjects. Half of them were patients who suffered from chronic ischemic heart disease (IHD), while in the others no symptoms or signs of this disease were found. Ventricular arrhythmias (VA) were detected in 196 subjects of the former and in 190 of the latter group. The Bureau of Statistics provided information concerning the individuals who died before December 31, 1976, the cause of their death and whether or not the death occurred in hospital or was ‘sudden’.We found that during the follow-up period, the rate of sudden cardiac death among the patients with IHD in whom AEM detected VA was higher than in subjects without VA. In the former group, there were 12 sudden cardiac deaths among 196 patients, while in the latter there were only 4 out of 248, a statistically significant difference. Sudden cardiac death was more frequent in individuals without IHD if AEM disclosed VA (4 sudden cardiac deaths among 190 subjects), as compared to individuals without VA (no sudden cardiac deaths among 254 subjects).