The following retrospective study analyzes 51 patients aged 45.8 +/- 11 years with infective endocarditis diagnosed from January 1, 1980-December 31, 1989. The aortic valve was mainly affected (59%). 92% of patients showed predisposing factors or a directly related incident. Positive blood cultures were found in 63% of patients. The dominating bacterium was streptococcus viridans (31%) with decreasing tendency compared to the previous decade, followed by staphylococcus aureus (22%) with significantly increasing tendency. Clinical and laboratory findings were not different from those of the previous decade. Main complications in the early period of disease turned out to be acute heart failure (69%) and arterial embolism (41%) which was dependent on the severity of disease. Mortality within the initial 6 months was significantly lower than in the previous decade (16% vs 31%). Patients undergoing heart-valve replacement within the first 6 months of disease (59%) had a mortality rate of 10%, which was significantly smaller than the 24% mortality rate of patients not being operated during the same period. Furthermore, patients with staphylococcus aureus endocarditis demonstrated a markedly worse early prognosis (6 month survival rate 28.6 +/- 17.2% vs 80.0 +/- 6.1% in patients with infective endocarditis other than staphylococcus aureus-related). Late mortality was not different in the above-mentioned subgroups with a 5-year survival of more than 80%. However, surgically treated patients significantly improved their functional class in the follow-up period over medically treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)