SUMMARYThis case report deals with an external - internal resorption. A 36 - year old man had a broken maxillary right second premolar. The radiograph showed a greetly expanded transparent surface on the root of the maxillary canine (Fig ; 2). This case was diagnosed as an external - internal resorption.The tooth was checked roentgenographcally after one year. The second radiograph revealed a larger transparent surface. It was including almost the entire root and reducing the dentin to a very thin lamelle (Fig : 3). Next day, this tooth was broken. The root was extracted and examined histologically.