We report on the synchronous detection of sarcoidosis in identical 22-year-old male twins. The patients visited a nearby physician because of fever and cough, were found to have abnormal chest shadows and thus admitted to our hospital. Both had swollen cervical and hilar nodes and lesions in both left and right lung fields, and also presented similar clinical symptoms. However, bilateral uveitis was observed only in the elder twin. Because epithelioid cell granulomas without caseous necrosis were histopathologically observed in tissue specimens from their cervical lymph nodes, the patients were given a diagnosis of sarcoidosis. Although they were positive for the HLA-D antigens DR 2 and DR 12, they were negative for DRw 52. an antigen that is considered to be quite common in Japanese sarcoidosis patients. Genetic factors were thought to be involved in the onset of sarcoidosis in these twins.