Sarcoidosis was diagnosed in a 55-year-old non-smoking woman because biopsy specimens of a subcutaneous tumor in her right cheek disclosed a noncaseating epithelioid granuloma. The patient had experienced exertional dyspnea and palpitation. Two months later, she was admitted because a Holter electrocardiogram (ECG) revealed bradycardia, 2:1 atrioventricular block (Mobitz II type) and ventricular premature beat (1.091 beats/day). ECG findings on admission changed from 2nd-degree to 3rd-degree atrioventricular block. A permanent pacemaker was implanted and the patient's symptoms subsided. Mediastinal uptake of Gallium-67 was observed and a defect of the cardiac septum was disclosed by Thalium-201 scintigram. Closer examination of the first Holter ECG revealed a Mobitz II type 2:1 atrioventricular block for about 3 minutes a day. Although the findings of the first Holter ECG initially disclosed a 2nd-degree atrioventricular block in our patient, a complete block developed within about 2 months after admission. In the follow-up of sarcoidosis patients, it therefore seems important to not only evaluate Holter ECG findings carefully, but repeat the examination at regular intervals.