This study evaluates primary hip replacement performed using a modified posterior approach through a limited posterior trochanteric osteotomy bone block that includes the insertions of the posterior capsule and short external rotators--as this may enhance secure reattachment of the posterior soft-tissue envelope and protect against postoperative instability. Sixty-eight consecutive primary hip replacements performed through a posterior trochanteric osteotomy were prospectively followed. Two were lost to follow-up before a minimum of 2 years after the arthroplasty; the remaining 66 hips were followed for a mean of 10 years (range: 2 to 15). The median Harris hip score improved from 43 to 84 points (p < 0.0001). Radiographic union of the osteotomy was confirmed in 64 hips (94%). Two episodes of early dislocation occurred 5 days and 8 months postoperatively; both were successfully managed nonoperatively without continuing instability. There were no cases of late instability. Posterior approach to the hip joint through a posterior trochanteric osteotomy is associated with high union rates and a low rate of late instability after hip replacement.