As the cost of health care remains a major concern for patients, providers, and payers, it has become increasingly important to evaluate resource utilization behaviors. The purpose of this study was to evaluate the utilization patterns of the emergency department in the ordering of lower extremity venous duplex ultrasound examinations for detection of acute deep venous thrombosis (DVT) and the use of D-dimer as a screening test in low-risk (by Wells criteria) patients. Estimated cost at our institution is $15 for the D-dimer test and $300 for the venous duplex ultrasound scan. All venous duplex ultrasound examinations that were ordered by the emergency department during the course of 10 days were evaluated. After-hours duplex ultrasound examinations were those ordered between the hours of 9 pm and 7 am on weekdays and between the hours of 4 pm and 7 am on weekends. Studies were evaluated for the patient’s presenting complaint, indication for duplex ultrasound as documented in the provider’s notes, results of the duplex ultrasound examination (positive vs negative for DVT), D-dimer studies, and Wells criteria scores. During this 10-day period, 68 lower extremity venous duplex ultrasound examinations were performed for emergency department patients, 28% of which were performed after hours (n = 19). Only 13% (n = 9) of these patients received concomitant D-dimer serum tests, of which 56% (5/9) of results were positive; 26 studies were bilateral, and only 5 studies were positive for acute DVT in one (n = 4) or both (n = 1) legs. Of 42 unilateral studies, only 9% (n = 4) were positive for acute DVT. Among patients with Wells criteria score <2, only 5 of 63 (8%) had a D-dimer sample sent. Among these, one had a positive duplex ultrasound scan. Five (8%) other positive duplex ultrasound scans occurring in the low-risk population did not have concomitant D-dimer samples sent. No patients with negative D-dimer results had acute DVT on duplex ultrasound examination. Based on the preliminary results of our pilot study, it appears there is significant overutilization of venous duplex ultrasound imaging by the emergency department for DVT screening with underutilization of D-dimer in low-risk patients. Use of D-dimer tests instead of duplex ultrasound scan in low-risk (Well criteria score <2) patients would have potentially saved $16,359 during a 10-day period, which would be approximately $597,104 per annum. Larger studies are recommended to examine the overuse of duplex ultrasound in the emergency department setting.