We present a rare case of bacterial endocarditis of tricuspid valve caused by temporary intracardiac pacing. The 48-year old male patient developed complete a-v block during the 1st day of acute inferior myocardial infarction. Intracardiac electrode was inserted for temporary pacing. After 4 days signs of bacterial endocarditis developed. Patient was markedly febrile, moderate tachycardia with gallop rhythm and systolic murmur of tricuspid valve insufficiency were present. Dullness to percussion was audible at the base of right lung. Hepato- and splenomegaly appeared during the second month of hospitalization. Laboratory tests revealed: elevated ESR, leukocytosis with a shift to the left, several blood cultures were positive to Staphylococcus aureus. On repeated chest X-ray patchy infiltrates with thin-walled translucent pools were visible. Transthoracic and transoesophageal++ echocardiography provided more precise informations. Bacterial vegetations were visualised on the tricuspid valve. Coronary angiography revealed proximal occlusion of the right coronary artery and 75-80% stenosis of the left circumflex artery. Antibacterial treatment guided by blood cultures was begun: vancomycin combined with netilmycin, then tienamycin and diflucan--after 10 weeks treatment was decided to be unsuccessful and the decision about surgical treatment was made. In extracorporeal circulation posterior left leaflet together with granular bacterial growths was excised. Septal and anterior leaflets were found normal. Cultures made of excised tissue were positive for Staphylococcus aureus and subsequent treatment with fluoroquinolones gave satisfactory result. Postoperative echocardiography revealed only small tricuspid valve insufficiency. Coronary by-pass surgery was performed later because of the high risk of simultaneous operation.(ABSTRACT TRUNCATED AT 250 WORDS)