Ten- to 20-year (average, 14 years) results of primary Charnley low friction arthroplasties performed in patients 50 years of age or younger (55 sockets and 53 femoral prostheses) were compared with those in patients older than 50 years (273 sockets and 273 femoral prostheses). The incidence of radiologic loosening of the socket, including revision cases, was higher in the younger (29.1%) than in the older patients (14.3%). The revision rate for aseptic loosening of the socket was higher in the younger (20%) than in the older group (4%). This poor performance of the socket may be attributable to the higher incidences of rheumatoid diseases and accelerated polyethylene wear in the younger patients. In contrast, only 3.8% of the femoral prostheses were radiologically loose, and none of them were revised in the younger patients. These figures were comparable with those in the older patients. Quality of structure of bone available for implant fixation may be important for the durability of the arthroplasty. It was considered inferior on the acetabular side and better on the femoral side in the younger patients than in the older. Continued use of the cemented Charnley femoral prostheses can be justified in young patients, although further research is required for the socket problem.