In a retrospective case-control review, we evaluated preoperative coagulation testing in patients undergoing major noncardiac operations to determine if routine testing benefits this group of patients. The platelet count (PC), prothrombin time (PT), and activated partial thromboplastin time (aPTT) in all patients undergoing major noncardiac surgery over a 22-month period were reviewed. The review was done both manually and by the computerized hospital information system. Major surgery was defined as procedures usually associated with significant bleeding. For each patient with abnormal results, another two control patients undergoing the same surgery and matched for age and gender were identified. Case and control patients were compared regarding a change in the management plan, use of blood products, blood loss, and bleeding complications by detailed chart review. A total of 828 patients undergoing nine different surgeries were reviewed. The incidence of abnormal PCs was 2.2% [95% confidence interval (CI) 1.2-3.2%] and that of abnormal PT/aPTTs was 2.1% (95% CI 1.1-3.1%). There were only two cases each of thrombocytopenia and prolonged PT/aPTT where the coagulation tests were not indicated clinically. Although (compared to controls) patients with abnormal tests had more changes in their anesthesia plan (36% vs. 2%, p < 0.001) and platelet or fresh frozen plasma transfusions (50% vs. 9%, p < 0.001), blood loss and the incidence of bleeding complications were not different. We conclude that the use of preoperative coagulation tests in patients undergoing major noncardiac surgery should still be guided by clinical assessment. The surgical procedure itself does not constitute an indication for testing.