We studied whether common shared environmental or behavioral risk factors, other than tobacco smoking, underlie both atherosclerotic diseases and cancer. We identified a group of 96,891 one-year survivors of acute myocardial infarct through the Danish Hospital Discharge Register between 1977 and 1989. We calculated the incidence of cancer in this group by linking it to the Danish Cancer Registry for the period 1978-1993. There was no consistent excess over the expected figures for any of the categories of cancer not related to tobacco smoking. Specifically, the rates of colorectal cancer in acute myocardial infarct patients were similar to those of the general population, as were the rates for hormone-related cancers, including endometrial and postmenopausal breast cancers. We found a moderate increase in the risk for tobacco-related cancers, which was strongest for patients with early onset of acute myocardial infarct and for female patients. Overall, there do not seem to be major shared environmental or behavioral risk factors for acute myocardial infarct and cancers, except for smoking, and there seems to be no common inherited susceptibility to the development of these diseases.