Background: Liver transplantation is currently accepted as a first line treatment for patients with end-stage acute or chronic liver diseases. Graft survival and overall patient survival have steadily improved since the first transplants were performed in the early 1960s, but a significant percentage of transplants develop complications related to vascular and biliary insufficiency. Graft ischemia after liver transplantation is associated with a high incidence of morbidity and mortality. Aim of the Work: was to evaluate the sensitivity of Duplex ultrasound in detection most of vascular complication after liver transplantation in correlation with CT angiography. Patients and Methods: The study was done from July 2017 until January 2018, where 20 cases who underwent living donor liver transplantation with post-operative complications. The cases were done at Dar Al Fouad Hospital and National Liver Institutes. The cases were 16 males and 4 females. All cases where admitted to post-transplanting intensive care unit in the postoperative period where a routine full laboratory and radiological assessment were done. The laboratory assessment included full liver function tests, kidney function tests, complete blood picture, and C-Reactive Protein. Immunosuppressant level and bilirubin level in drains had also done. Results: The patient age ranges from 43 to 80 years with the mean age of 61.5 years. Eighteen cases had hepatitis C related cirrhosis (90%) One case had veno-occlusive disease related cirrhosis (Budd Chiari syndrome). One case was Wilson disease. About 95% of cases were suffering from end stage liver disease. The results we have reached are that Doppler U/S sensitivity in diagnosis of these complications is about 75%. Conclusion: It could be concluded that gray-scale US and color Doppler are the investigations of choice in postoperative liver transplantation. They can be used as routine steps in the assessment of liver transplant graft postoperatively in recipient patient as early as possible within the first 3 days after operation and used as a late follow up, as they are noninvasive, safe, cheap, and accurate. Routine use of gray- scale US and color Doppler showed to minimize the impact of postoperative complications and maximize both graft and recipient patient survival.