Septicaemia on endovenous pacemaker electrodes is infrequent and difficult to detect. We report the case of a 64-year old woman with a diagnosis of prolonged fever that dragged on for several months before infection of her pacemaker was considered, then confirmed. Repeated Staphylococcus epidermidis isolates from blood cultures were no longer regarded as contaminations, and transoesophageal echocardiography revealed the presence of a "mass" on her endocavitary electrode, which had not been visualized on several previous échocardiographies. Surgical removal of the electrode was soon required in view of multiple septic emboli despite a bacteriologically effective antibiotic therapy. The outcome is favourable after a 6-month follow-up. The authors review the diagnostic and therapeutic problems created by infections on electrosystolic exciting electrodes.