Periacetabular osteotomy has become the procedure of choice in many centers for the treatment of symptomatic hip dysplasia in young patients without severe secondary hip arthritis. Reorientation pelvic osteotomy has the potential for large blood loss and the need for blood transfusion. Between 1996 and 2003, 108 periacetabular osteotomies (107 patients) were performed by one of the authors. There were 84 females and 23 males with an average age of 30 years at the time of surgery. The overall allograft transfusion rate was 20% (21/108). Ninety-four percent (101/108) of the patients received transfusions including autologous blood, intraoperative cell saver, and postoperative allograft transfusion. The average transfusion amount (cell saver and allograft) was 2.14 units per patient. The risk for transfusion between males and females was not significantly different. The data from this study suggest that the vast majority of patients undergoing periacetabular osteotomy will require some form of transfusion, with 20% requiring allograft blood. The need for allograft blood will be minimal if the preoperative hemoglobin is greater than 12 g/dL.