We report a case of an intravenous drug user who already had a tricuspid bioprosthesis implanted after an infective endocarditis with massive tricuspid regurgitation one year ago. Now he presents with a large mass on the atrial side of the bioprosthesis that led to obstruction; hemocultures contained Enterococcus faecalis. After one-week therapy with antibiotics, aspirin and enoxaparin the mass untangled to a swinging structure and moderate to severe triscupid regurgitation developed; surgery appeared inevitable. After two weeks however the mass was gone, tricuspid insufficiency subsided and the patient became asymptomatic. This case illustrates the potential but controversial role of anticoagulation in the treatment of patients with infective endocarditis.