Between March 1971 and April 1976 37 patients were seen with manifest bacterial endocarditis. The main signs were high temperature and cardiac murmurs whereas other "classical" signs such as splenomegaly, anaemia, leucocytosis, and positive anti-streptolysin titres were much less frequent. In 35 cases bacteriological proof was possible. As causative organism a total of 30 gram-positive organisms (of which 15 were Streptococcus viridans and 8 were Staphylococcus species) and 10 gram-negative bacteria (4 of which were Pseudomonas aeruginosa) could be demonstrated. Treatment was mainly with beta-lactam and/or aminoglycoside antibiotics. Use of the combination of penicillin and streptomycin or gentamicin was based on the results of in-vitro bactericidal activity. The main complications were emboli, penicillin allergies, pulmonary involvement and cardiac complications. 13 patients died; the main cause was cardiac failure which was irreversible even despite operative valve replacement during the acute infection in two cases.