24 hour ambulatory electrocardiography was performed in a representative group of people born in 1897. Out of 73 people included in the study, 22 were without known heart disease, 15 had definite ischaemic heart disease (IHD) and 36 symptoms of possible cardiac origin. An R-R interval in excess of 2000 ms was seen in only 3 subjects and Wenckebach A-V block in only one. One subject without a history of syncope had a nocturnal episode of complete A-V block with an escape interval of 8000 ms. The most striking difference between healthy subjects and patients with IHD was the higher number of patients with more than 1000 ventricular premature beats (VPBs) per 24 hour and ventricular couplets compared with the number of healthy subjects with such findings. At follow-up two years later 11% had died, with the highest mortality in patients with IHD (33%), and out of 8 patients with IHD who had more than 1000 VPBs per 24 hour, 4 (50%) had died compared with only one (14%) of those with less than 1000 VPBs. Our results seem to indicate that more than 1000 VPBs per 24 hour is a very unusual finding in healthy 85 year old individuals. When it occurs in very old people, it is usually in connection with IHD, and in this setting it signifies a poor prognosis.