A case of bacterial endocarditis caused by Moraxella catarrhalis in an appa
rently immunocompetent Greek male is presented, which was diagnosed after a
2-month history of low-grade fever of unknown origin. The agent seems to b
e a rare pathogen, but due to the high mortality rate, it should always be
considered in the differential diagnosis of relevant cases. Beta-lactamase
production by many strains complicates the choice of antibiotic.