Intrathoracic surgery for retained endocardial electrodes was performed in 12 patients; the indication for electrode removal was Staphylococcus aureus or epidermidis infection in 11 patients and malfunction in one patient. Two operations had to be performed on emergency basis. One was carried out because of myocardial rupture and cardiac tamponade after a tightly fixed electrode lead had been pulled out. The other patient was operated on because of ventricular arrhythmia arising from a malfunctioning lead which had slipped back completely after transsection into the right ventricle. Ten patients underwent elective surgery; cardiopulmonary bypass was needed in 6 of these. In one case a mitral prosthesis was replaced because of infection. Radical treatment is recommended for pacemaker infections and the removal of electrodes should be considered even if intrathoracic surgery is required.