There is mounting evidence that patients with systemic lupus erythematosus (SLE) are prone to disseminated neisserial infections. We describe the first proven case of gonococcal endocarditis affecting the pulmonary valve in a patient known to have SLE. The clinical clues and pitfalls in diagnosis are discussed, and the role of echocardiography is highlighted. Possible reasons for the association of gonococcal endocarditis with SLE include pre-existing Libman. Sacks endocarditis, complement deficiency and abnormalities of the reticuloendothelial system.