We investigated the usefulness of 24-h Holter monitoring for identification of myocardial involvement in 38 patients with sarcoidosis, including 12 patients with cardiac sarcoidosis, and 58 healthy controls. Ventricular ectopic beats (VEB) > or = 100 beats per day were detected in 8 (67 percent) of 12 patients with cardiac sarcoidosis, in 2 (8 percent) of 26 patients without cardiac sarcoidosis, and in 3 (5 percent) of 58 healthy controls. Holter monitoring was associated with a sensitivity of 67 percent and a specificity of 62 percent for cardiac sarcoidosis in the overall study population. In patients with sarcoidosis, specificity was 80 percent. Lown's grade 4 A and 4 B VEBs were detected in 8 (67 percent) of 12 patients with cardiac sarcoidosis, in 2 (8 percent) of 26 patients with sarcoidosis without cardiac involvement, and in 2 (3 percent) of 58 controls. Holter monitoring was associated with a sensitivity of 67 percent and a specificity of 80 percent for identification of cardiac involvement in patients with systemic sarcoidosis. Our findings suggest that 24-h Holter monitoring provides a convenient and inexpensive means of noninvasive screening for cardiac involvement in generalized sarcoidosis, even in patients and outpatients who are without symptoms.