In a population of 930,000 inhabitants all records of native valve infective endocarditis diagnosed in the decade 1980-89 were reviewed. One hundred and thirty-two cases were found, of whom 23 were not diagnosed until postmortem. Median prehospital duration of symptoms was 20 days (range 0-180) and median in-hospital diagnostic delay five days (range 0-54). Known cardiac disease was found in 42%, possible portal of entry in 33%, but in 36% no predisposing factors were found. During the clinical course 55% experienced cardiac failure and 17% embolic episodes. Surgery was required in 19 patients. Of 111 culture positive cases, streptococci were found in 61 and staphylococci in 45 cases. Overall mortality was 33% with a mortality of clinically diagnosed cases of 18%. Native valve endocarditis is thus associated with a significant mortality in part due to significant diagnostic delays and a large number of post-mortem diagnosed cases. Only by securing a high level of alertness towards endocarditis can we expect a reduced mortality.