We studied 342 potentially "high-risk" patients, including patients with severe heart disease, elderly patients, children, and pregnant women, to determine the incidence of complications related to phlebotomy. Our patients had an adverse reaction rate associated with blood donation of 4 percent, which is no greater than would be expected among normal volunteer blood donors. No patient experienced a dangerous complication associated with phlebotomy. We conclude that many patients currently denied the opportunity to donate blood preoperatively are actually suitable candidates for autologous blood transfusion programs.