Unicompartmental knee arthroplasty is an attractive concept that offers several potential advantages over total knee replacement arthroplasty or proximal tibial osteotomy. Fifteen unicompartmental knee arthroplasties were performed between July 1983 and January 1990 at Department of Orthopaedic Surgery, Seoul National University Hospital. There were 1 male and 12 females. Bilateral unicompartmental knee arthroplasties were performed in two patients. Average age of the patients with 61 years. The mean follow-up was 1.8 years ranging from one to seven years. The replaced compartments were all medial side. The results were evaluated using the Hospital for Special Surgery rating system. Excellent results were obtained in 9 knees and good results were obtained in 5 knees. One knee was rated as fair result. Appropriate patient selection and careful surgical technique will provide good to excellent results while preserving bone stock and ligamentous structures for revision if necessary.