Objective To evaluate the outcome of Precision-fit Surface Hemiarthro-plasty in treatment of the femoral head osteonecrosis . Methods We reviewed the results of fouty-eight Precision-fit Surface Hemiarthroplasties in patients who were forty years old or younger at the time of the operation and were followed for a minimum of three years or until the prosthesis failed. All of patients were diagnosed femoral-head necrosis with thirty-five at Ficat stage III and thirteen at stage IV;their acetabula were relatively normal. Results The mean duration of follow-up was 5.2 years. Theaverage UCLA hip score at follow-up was improved significantly (p=0.001), survival rate was 83％.Conclusions Precision-fit Surface Hemiarthro- plasty of the hip had a satisfactory result in treatment of the femoral head osteonecrosis.