The frequency and type of some abnormal ECG findings in 86 consecutive patients with intrathoracic sarcoidosis were studied and compared with 86 age- and sex-matched healthy controls. All ECGs from the patients and controls were mixed and evaluated blindly by one of the investigators. Ectopic beats were seen in 6 patients in the sarcoidosis group and in 3 individuals in the control group. Patients with stage III sarcoidosis had more conduction defects compared with stage I and II patients and with the controls. Repolarization disturbances were found in 17 patients and 6 controls. These disturbances were more common in patients with stage I and II than in those with stage III sarcoidosis. The total number of patients with some ECG abnormality was 27 compared to 12 controls.