Reduction in bleeding after heart-lung transplantation. The importance of posterior mediastinal hemostasis. To reduce perioperative hemorrhage following heart-lung transplantation, several technical modifications were introduced in June 1988 to secure better posterior mediastinal hemostasis. The intraoperative and postoperative use of blood and blood products, as well as the chest tube drainage in the first 24 hours postoperatively, were compared in the seven patients operated on since June 1988 with the nine patients operated on before that date. Significant (p less than 0.05) reductions were demonstrated in the intraoperative and postoperative transfusion of packed cells, in the postoperative administration of fresh frozen plasma, and in the chest tube drainage within the first 24 hours postoperatively. The one-month and total hospital mortality rates were 6 percent and 12.5 percent, respectively. It is concluded that newer techniques to obtain optimal posterior mediastinal hemostasis have significantly reduced blood loss following heart-lung transplantation in our experience and have contributed to our excellent early postoperative results. 