The prediction of patients who are at sufficiently high risk of postoperative deep venous thrombosis to indicate perioperative antithrombotic prophylaxis has traditionally used only clinical risk factors. The associations of preoperative and/or postoperative haemostatic tests with postoperative deep venous thrombosis are reviewed. In general, the results support the biological concept of a preoperative and postoperative prothrombotic tendency in patients who develop deep venous thrombosis. Increased levels of coagulation activation markers and decreased assays of fibrinolytic potential show consistent relationships to postoperative deep venous thrombosis. At present, however, the clinical utility of such tests is unproven; so that at present they cannot be advocated for routine preoperative or postoperative screening.