We asked whether cementless total hip arthroplasties that made use of alumina-on-highly cross-linked polyethylene bearings would improve hip score and functional activity and reduce the prevalence of polyethylene wear, osteolysis, and aseptic loosening. Consecutive primary total hip arthroplasties were performed in fifty patients (a total of sixty hips among thirty-four men and sixteen women) who were younger than thirty years of age. The average age at the time of the index arthroplasty was 28.3 years (range, twenty-one to twenty-nine years). The average follow-up was 10.8 years (range, ten to twelve years). Osteolysis and polyethylene wear rates were evaluated with use of radiography and computed tomography. The mean Harris hip score, which was 38 points (range, 6 to 45 points) preoperatively, had improved to 95 points (range, 85 to 100 points) at a mean follow-up time of 10.8 years. The mean penetration (and standard error of the mean) of the polyethylene liner was 0.031 ± 0.004 mm per year. No hip had osteolysis or aseptic loosening. At a minimum of ten years and an average of 10.8 years postoperatively, the current generation of cementless acetabular and femoral components with alumina-on-highly cross-linked polyethylene bearings was functioning well and was not associated with the development of osteolysis in our group of patients younger than thirty years of age. While the long-term prevalence of polyethylene wear and osteolysis remains unknown, the midterm data are promising.