In a prospective study of 61 patients who were undergoing elective total hip replacement, the accuracy of real-time B-mode ultrasonography (B-US) in the diagnosis of postoperative deep vein thrombosis (DVT) was compared with blindly assessed bilateral ascending phlebography. The overall sensitivity and specificity of ultrasound was 71 and 94%, and the positive and negative predictive values were 77 and 92%, respectively. The sensitivity and specificity for diagnosis of proximal DVT was 73 and 96%, respectively. Thrombi smaller than 1 cm were not detected. It is concluded that B-US may be used as a screening test for postoperative DVT after elective hip surgery.