The authors have been using Swanson's prostheses for MP joint replacement in rheumatoid arthritis since 1968. After thirteen years of experience, they present an analysis of these prostheses from a clinical and radiological point of view. 88 joints replacements in 20 patients are reviewed. These operations were performed between 1968 and 1976. The average follow-up is nine years. The authors compare their results with those obtained in a previous study made in 1975. They show that a replacement arthroplasty with a Swanson type prosthesis, imparts considerable benefits to the patient in the form of complete disappearance of pain, improvement in function, and a more normal looking hand, in spite of radiologic deterioration.