Bacterial endocarditis (BE) is one of the most severe complications of hemodialysis (HD). The aim of the study was to analyse frequency and severity of BE in patients treated with HD in our dialysis unit. During the period 1969-1993276 patients were treated with HD in Gdańsk. In 23 cases (9F, 14M) HD treatment was complicated with BE. Patients were divided into two groups on basis of diagnostic criteria: I-13 patients (5F,8M) with BE diagnosed by means of clinical picture and positive blood culture.; II-10 (4F, 10M) with diagnosis additionally confirmed by echocardiography. In patients from group I BE was observed more often during the first 2 years of HD. In group II during 3-5 years of dialysis therapy, gram negative microorganisms were the most frequent etiological factors. The mean period of antibiotic therapy was 35 days. In all patients from group II changes in the bicuspid valve, in 60% of them additionally in aortic valve and in one patient also in the tricuspid valve were observed. In five patients changes in the parietal endocardium were also present. Development of organic valvular changes was observed in nine patients. Seven of 22 patients died during the acute phase of BE and two others from complications connected with BE. The longest survival of patients after BE was over 10 years. CONCLUSIONS 1. The threat of BE in patients treated with HD decreased between 1987 and 1993 in comparison with the initial period of our HD station operations.(ABSTRACT TRUNCATED AT 250 WORDS)