The antecedents of myocardial infarction have been reviewed in 102 patients (117 episodes) undergoing a program of rehabilitation. The year prior to the first attack was characterized by business and social problems, with some weight gain; in the week before the attach there was added tiredness, poor general health and, in some cases, increasing anginal pain. Heavy lifting and/or unusual exercise were common immediately before or during an attack; five attacks were related to the shovelling of wet snow.Both bed and the normal place of work were uncommon sites for an attack. More than 50% of patients had 30 minutes' warning of infarction. The relevance of these findings to a safe program of therapeutic exercise is discussed.