Abstract To assess the role of routine Doppler ultrasound in the detection of clinically unsuspected vascular complications in the early postoperative phase after orthotopic liver transplantation (OLT), the findings of 858 routinely performed Doppler ultrasound examinations were analyzed in 268 transplants. At various time intervals after OLT, we encountered 46 abnormal Doppler findings: hepatic artery (thrombosis), portal vein [anastomotic stenosis, (non)occlusive thrombosis or reversed flow], inferior vena cava [anastomotic stenosis with reversed flow, no flow, or (non)occlusive thrombosis], and hepatic veins (to-and-fro flow or stenosis with reversed flow) in 14, 20, 9, and 2 transplants, respectively. Most of these abnormal Doppler findings were confirmed by angiography, cavography, or surgery. The positive predictive value for hepatic artery thrombosis (HAT) was 12 out of 14, or 86%. In the first 2 weeks after OLT, routine Doppler ultrasound revealed 20 of the 46 abnormal findings (43%). Clinically unsuspected complications of the hepatic artery, portal vein, inferior vena cava, and hepatic veins were found in 9 of the 14 (64 %), 6 of the 20 (30%), 3 of the 9 (33%), and 2 of the 2 (100%) transplants, respectively. The highest incidence -nine vascular complications - was found on the 1st day. On each of the remaining days (except for the 2nd and 9th days), one or two vascular complications were detected. HAT was found mainly in the 1st week. Vascular complications developed independently or concomitantly. We conclude that routine Doppler ultrasound is very important for the detection of clinically unsuspected vascular complications, particularly HAT, in the first 2 weeks after OLT. We recommend routine Doppler ultrasound of all hepatic vessels every 3 days in the early postoperative phase after OLT. Special attention should be paid to the 1st day.