To test the hypothesis that those who ever passes a period of being overstrained are at elevated risk to suffer from myocardial infarction, the question `Have you ever been overstrained? was included in a prospective study of 3877 males, aged 40-65, who were free of coronary heart disease. This cohort was followed during a mean period of 4.2 years. The age-adjusted relative risk associated with `ever been overstrained' was found to be 1.81 (p <.01).