The incidence of invasive infections caused by Streptococcus pneumoniae has increased dramatically in Norway the last 5-10 years. We describe a patient with a pneumococcal endocarditis of the tricuspic valve who illustrates some of the diagnostic and therapeutic problems often connected with right-sided endocarditis. We also review literature on pneumococcal endocarditis. Since the introduction of antibiotics, the incidence of pneumococcal endocarditis has decreased significantly. The most important predisposition still seems to be alcoholism. Cases of pneumococcal endocarditis require prolonged and consistent antibiotic treatment. Rapid destruction of the valves is typical, and often demands surgical intervention at an early stage. So far no multiresistant pneumococci have been observed in Norway. The increased incidence of serious pneumococcal infections has recently made it necessary to recommend that pneumococcal vaccine be given on wider indications.