We assessed the OrthoPAT Orthopedic Perioperative Autotransfusion System (Zimmer Inc, Warsaw, Ind) in reducing the need for allogeneic blood in hip or knee arthroplasty. Patients (N = 398) were divided into 5 cohorts: unilateral primary hip (n = 131), unilateral revision hip (n = 38), unilateral primary knee (n = 179), unilateral revision knee (n = 26), and bilateral primary knee (n = 24). Primary or revision hip arthroplasties with no preoperative autologous blood donation, knee arthroplasties with no preoperative autologous blood donation, and unilateral primary hip arthroplasties were 2.7, 2.3, and 2 times less likely (P < .05), respectively, to use allogeneic blood with OrthoPAT. We conclude that OrthoPAT use significantly reduced the risk of receiving allogeneic blood transfusions in defined patient subsets.