The results of total hip arthroplasty (THA) in young patients with osteoarthritis have been discouraging. In this prospective study, 78 patients (89 THA) were consecutively included and followed for 12 to 15 years (mean, 12.2 years) after the index surgery with the uncemented Ultralok femoral prosthesis (Zimmer, Wiltshire, UK). Age at surgery was 59.8 years (40 to 76). The follow-up process included an in-office clinical evaluation and a radiographic evaluation. A cumulative survival of 96.6% (with the end point defined as revision of the femoral component because of mechanical or radiographic loosening) was found for the femoral component after13 years, and all unrevised components were radiographically fixed by bony ingrowth. Twenty-three well-fixed stems had to be removed for femoral head damage at the time of the acetabular revision. The results of this comparatively large series show that good fixation has been achieved with a proximal titanium mesh and grit-blasted titanium alloy stem.