The efficacy of routine screening coagulation tests was studied to identify occult coagulopathies in patients prior to elective general and vascular surgery procedures. The efficacy of screening tests was compared to that of indicated tests performed for predefined clinical indications, which were elicited by history and physical examination and a detailed coagulation history questionnaire. Tests were prothrombin time (PT), partial thromboplastin time (PTT), platelet count (PC), and bleeding time (BT). Of 514 screening tests done in the 282 patients, 4.1% were abnormal, but none of them identified a clinically significant coagulopathy. Of the 605 indicated tests, 7.4% were abnormal, and all significant coagulopathies were found in this group. The study shows that preoperative screening tests for coagulopathies not suspected on the basis of detailed clinical information are unnecessary and should not be done. In the authors' institution 46% of screening coagulation tests could be eliminated.