BACKGROUND: The long-term prognostic value of systolic murmurs revealed by heart auscultation has previously not been published. In this survey the prognostic value of systolic murmurs has been studied in relation to coronary heart disease and aortic valve operations. MATERIAL AND METHODS: During 1972-75, a cohort of 2014 apparently healthy men (40-59 years) from five companies in Oslo, Norway underwent heart auscultation under standardized conditions. Systolic murmurs were graded from I to VI. The men were prospectively followed up for 21.5 years in order to study the frequency of aortic valve operations, myocardial infarctions and coronary bypass operations. RESULTS: Modest systolic murmurs (grade I-II, n = 441) were associated with an unadjusted relative risk of 5.4 (95% CI 2.1-14.0), and moderate to strong murmurs (grade III-IV: n = 32) with a relative risk of 114.6 (95% CI 44.9-292.1) for aortic valve operation over the course of 21.5 years. The incidence of myocardial infarctions did not show any significant relationship to murmurs. Among those who underwent aortic valve surgery and who had a baseline murmur > or = III, a fourfold increase in bypass operations was observed. INTERPRETATION: Apparently healthy middle-aged men with systolic murmurs grade III or IV revealed by heart auscultation should be followed up carefully with regard to future need for aortic valve surgery. The increased frequency of coronary bypass operations among those with systolic murmur grade III or IV is possibly a result of aortic valve and bypass surgery being performed simultaneously.