FIBROUS DYSPLASIA occupies a rather prominent position among those bone lesions which frequently owe their detection to an incidental radiologic examination. In the absence of subjective symptoms or objective clinical findings, the radiologic evidence is then the only indication of skeletal disease. The accuracy of the radiologic diagnosis is not well established, and many investigators have expressed the view that the roentgen findings are not specific and therefore not reliable. Schlumberger (20) emphasized the fact that in none of the sixty–nine cases studied by him at the Army Institute of Pathology during World War II was the possibility of fibrous dysplasia entertained by the radiologist. Our experience at Brooke General Hospital has led us to believe that the diagnosis can be arrived at with relative ease on the basis of the radiologic appearance of fibro-dysplastic lesions. Our observations do not indicate, however, that the radiologic features of fibrous dysplasia are always specific or pathognom...