Fifty-seven patients suffering from acute bleeding were studied with multiple (25) different coagulation tests. Twenty-three of the 57 patients underwent operation, including six in whom operative intervention was delayed in order to improve coexistent hematologic abnormalities. Bleeding in five of these six "delayed" subjects and, overall, in 20 of these 23 patients was successfully controlled by operation. The remaining 34 patients, so-called "medical bleeders," included eight originally considered for operation, but in whom this was avoided as a result of the coagulation profile. Medical treatment successfully arrested the bleeding in six of these eight patients. The study demonstrates the value of adequate preoperative coagulation testing in recognizing and correcting obvious hematologic abnormalities, minimizing unnecessary operations, and reducing the possibility of catastrophic intraoperative hemorrhage.