SOME pathologists believe that sarcoidosis is a type of noncaseating tuberculosis, while others maintain that it is a separate disease entity of unknown origin. The similarity of the clinical manifestations of sarcoidosis and tuberculosis and the resemblance of the biopsy findings frequently make the differential diagnosis of these diseases difficult. In cases in which the presence of acid-fast bacilli can be demonstrated, there is no question about the diagnosis; but in the absence of clinical signs of tuberculosis and in cases in which examination fails to disclose Mycobacterium tuberculosis, the biopsy findings may be considered characteristic of either tuberculosis or sarcoidosis. I shall report 2 cases of sarcoidosis of the orbit which have been observed at the Mayo Clinic. REPORT OF CASES Case 1. —A white woman aged 54, a native of Puerto Rico, came to the Mayo Clinic on Jan. 21, 1926 because of a mass in the left