Adenomatosis coli is a very interesting disease accompanied by a number of associated stigmata in the mandible. If left ignored, colonic lesions in patients with this disease proceed almost entirely to malignancy. Hence, detection of the stigmata is very important. The panoramic radiographs of 26 patients diagnosed as adenomatosis coli at the 2nd Department of Surgery, Hamamatsu University School of Medicine from 1978 to 1988 were compared with those of 264 controls. Osteomatous lesions were present in 62% of the patients with adenomatosis coli and 14% of the controls. Pantomographic comparison of the numbers and areas of the osteomatous lesions between the adenomatosis coli and control groups indicated that specific pathognomonic symptoms were demonstrated in panoramic radiographs of approximately 42% of the patients with adenomatosis coli.