Objective: Evaluate the diagnostic accuracy of 256 slices computed tomography (CT) coronary angiography (CA) (multidetector CT [MDCT]) in the assessment of native coronary arteries and grafts in post coronary artery bypass graft (CABG) surgery Egyptian patients. Patients and Methods: It included 70 patients with a history of isolated CABG with recurrent chest pain. We excluded patients with a history of redo CABG or other open heart surgeries, renal impairment, severe claustrophobia, chronic liver disease, dye allergy, tachycardia with contraindication to beta blockers (BB), pregnancy. All patients were subjected MDCT and CA. Both examinations were done within 3 months. Results: In our study, 161 grafts evaluated (63 left internal mammary artery [LIMA] in situ grafts, 5 right internal mammary artery (RIMA) and 2 radial grafts, and 91 venous grafts). CA failed to detect 3 LIMA and 7 venous grafts. All were seen only by MDCT. For grafts CT compared to CA has sensitivity (91.5%, 84.8%), specificity (98%, 100%), accuracy (95.65%, 96.9%), positive predictive value (PPV) (96.43%, 100%), and negative predictive value (NPV) (95.24%, 96.2%) in the assessment of significant stenosis and total occlusion of grafts, respectively. For grafted vessels CT has sensitivity (94%, 100%), specificity (98%, 100%), accuracy (96.94%, 100%), PPV (95.92%, 100%), and NPV (97%, 100%) in the assessment of significant stenosis and total occlusion of grafted vessel, respectively. For native vessels CT has sensitivity (100%, 97.7%), specificity (84.2%, 98.4%), accuracy (97.14%, 98.1%), PPV (96.6%, 97.7%), and NPV (100%, 98.37%) in the assessment of significant stenosis and total occlusion of native vessels, respectively. Conclusion: Our study demonstrated a high diagnostic accuracy of MDCT for the assessment of bypass grafts and grafted or native coronary arteries compared with CA. Detection of grafts or native vessels occlusion was better than detection of substantial stenosis. MDCT is a good negative test for native vessels as it has a high sensitivity since it tends to overestimate stenosis degree, so patients with negative MDCT angiographic results mostly have patent vessels. Keywords: Coronary artery bypass grafts, multidetector computed tomography, noninvasive coronary angiography