Sixty patients who received 75 consecutive liver grafts and had routine Doppler sonography monitoring in the early postoperative period (three times a day) were reviewed for vascular complications. Thrombosis of the hepatic artery was detected in seven patients (3, 4, 20, 24, 48, 70 and 84 h after liver transplantation) and was then confirmed by emergency laparotomy in six cases. In one patient, thrombosis was verified by angiography before laparotomy. In two patients thrombectomy was successful, in five patients retransplantation had to be performed. Portal vein occlusion was detected in three patients (24, 26 and 90 h after transplantation) and all were successfully treated by thrombectomy and partial arterialization of the portal vein. Colour Doppler sonography was associated with no false-positive or -negative results. The specificity was 100% for the diagnosis of hepatic artery and portal vein thrombosis. In our opinion colour Doppler sonography will be able to replace time-consuming angiography in vascular diagnostics in the early postoperative phase after liver transplantation. Furthermore, there is evidence that frequent use of this non-invasive technique permits early detection of clinically unsuspected vascular complications and subsequent immediate relaparotomy, which is linked to a reduction in the rate of retransplantation.