For one year (1 September 1975-31 August 1976) an analysis was made of all deaths occurring outside hospital in the Gothenburg area (population 480 000). The total number of deaths was 1309. It was found that 675 (52%) of these deaths were caused by ischaemic heart disease (IHD), while 54 (4%) were caused by other heart diseases. The circumstances preceding death were analyzed in 363 cases representing all autopsied subjects under 75 years of age who died from IHD (autopsy rate 95%). Of these, 68% died at home, 4% during transport to hospital, and 4% at work. 214 (59%) of the deaths were witnessed, and in 189 (52%) cases, an ambulance had been called. 111 (52% died within 1 min of the onset of symptoms. 23 subject were in ventricular fibrillation on arrival at hospital. 11 of them were resuscitated, but only 3 were discharged alive. Additionally 12 of the non-autopsied subjects who died from IHD and 11 who died from other heart diseases had been witnessed and an ambulance had been called. In summary, 212 subjects who died outside hospital from heart disease in one year in Gothenburg died witnessed, and an ambulance was called. This should be the maximum annual number of cases of cardiac arrest outside hospital which it is possible to reach with a mobile coronary care organization within the time limit for effective resuscitation attempts.