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: to evaluate the sensitivity and specificity of Duplex ultrasound in detection most of vascular complication after liver transplantation in correlation with CTA. Patients and Methods: The study was done from Aug. 2017 until Aug. 2018, where 50-55 cases who underwent living donor liver transplantation with post-operative complications. The cases were done at Ain Shams University Hospital and other private hospitals. 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 36 to 53 years with the mean age of 45 years. Most cases have cases had hepatitis C related cirrhosis (90%). One case had veno-occlusive disease related cirrhosis (Budd Chiari syndrome). 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 83.8% and CTA sensitivity is about 100%. Conclusion: It could be concluded that colour duplex is 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 duplex showed to minimize the impact of postoperative complications and maximize both graft and recipient patient survival and if any complications suspected, it can be confirmed by CTA