Surgical procedures on patients with congenital disorders of blood coagulation can be performed with a high degree of confidence and an acceptable incidence of complications. During the period 1960-1975, 42 patients with congenital disorders of blood coagulation underwent 94 operative procedures at the New York Hopital-Cornell Medical Center. The coagulation defect was diagnosed preoperatively, in nearly all patients. Careful hematologic management, including specific factor replacement, is essential. The importance of meticulous hemostasis at surgery and careful monitoring of blood coagulation in the postoperative period is strongly emphasized.