This retrospective study reviews 155 bilateral total knee arthroplasties, of which 99 were simultaneous and 56 staged. The results revealed that blood loss and postoperative blood requirements were higher in the simultaneous group, with 60% requiring homologous blood. The simultaneous approach was advantageous for a reduction in hospital stay, physical therapy, and resultant hospital costs. The complication rate was similar for both groups when examining pulmonary embolism, wound problems, infection, deep venous thrombosis, and death. The authors' incidence of fat embolism syndrome was similar for both groups but higher than that reported in the literature. Attempts with present preoperative evaluation cannot predict the incidence of fat embolism syndrome. A more invasive preoperative workup may identify those at risk. Preoperative marrow stimulants and the use of reinfused blood may eliminate the use of homologous blood in the simultaneous group.