The authors retrospectively reviewed 40 patients who underwent 52 Phemister bone grafting procedures for nontraumatic aseptic necrosis of the femoral head to better define indications and to evaluate long-term effectiveness of the procedure. The minimum follow-up period was 2 years, and evaluation included physical examination, Iowa hip rating, and radiographs utilizing Marcus and Enneking's staging system. At 2 years following grafting, 13 (76%) of the 17 hips grafted at stage II progressed at least one stage, as did 7 (64%) of the 11 hips grafted at stage III, and 19 (86%) of the 22 hips grafted at stage IV. At the latest follow-up evaluation, 15 (88%) of the 17 hips grafted at stage II progressed at least one stage (follow-up period, 2-10 years), as did 9 (82%) of 11 hips grafted at stage III (follow-up period, 2-10 years), and 21 (95%) of the 22 hips grafted at stage IV (follow-up period, 2-12 years). Twelve (23%) of the 52 hips underwent femoral head or total hip arthroplasty, and the overall Iowa hip rating was 72. The authors' experience confirms reports of other series that do not recommend Phemister bone grafting once collapse is present. The role of structural bone grafting as a temporizing procedure is uncertain.