There is a definite value in a surgical arthroplasty for the ankylosed proximal interphalangeal joint. The existing literature does not give an adequate evaluation of the procedure and its results, and the reported series have been small. As an aid in the problem of the stiff and deformed finger, the knowledge gained from thirty cases has been outlined. The longest period of follow-up has been seven years. The disabling factors have been fracture, dislocation, and infection at the proximal interphalangeal joint. Arthroplasty has been found valuable as a method of reconstruction for deformities of the proximal interphalangeal joint in selected cases. No attempt has been made to replace the use and technique of joint arthrodesis in the flexed position of function. Criteria in the selection of cases must include: (1) ankylosis in a position of great deformity; (2) no damage to the tendons which produce motion at the middle joint; and (3) a high degree of motivation in the patient to regain mobility. The most simple technique, consisting in resection of the distal portion of the proximal phalanx, has beeen used. It is not believed necessary to use interposed tissue, metals, or plastic material for the formation of the new joint. Skeletal traction has been maintained for six weeks. An active, closely supervised program of rehabilitation has been found necessary. In the authors' first thirty patients, there has been improvement in 83 per cent. They hope to report better results in the future.