Background: accurate selection of the patients with known or suspected coronary artery disease (CAD) who will benefit from additional CT-based attenuation correction (CT-AC) images to gated 99m Tc -MIBI myocardial perfusion scintigraphy (MPS) is mandatory to compromise the increased sensitivity demand for the unnecessary radiation doses exposure concerns. Aim of the work: to evaluate the value of added CT-AC to gated MPS in the clinical diagnosis of CAD for appropriate selection of the patient who will benefit from this additive technique. Patients and methods: 90 patients (53, SD ± 12 year-old, 66%males) were retrospectively included in the study. Two days protocol gated MPS and additional CT-AC images were performed for all patients. The final clinical diagnosis wasreached by consensus after interpreting the gated MPS images and correlating them with the clinical risk factors and other available cardiac diagnostic modalities. Comparison was done between the final diagnosis and the CT-AC images to evaluate the performance of the latter. Results: 159 segmental perfusion defects were elicited; 93 (58%) and 66 (42%) perfusion defects were finally interpreted as attenuation artifact and true ischemic defects respectively. The CT-AC images show good performance with 100% sensitivity and specificity in the inferior and lateral walls perfusion defects while it shows poor performance in the anterior and septal walls due to false positive results resulting in reduced specificity of 75 %.Conclusion: CT-AC is a fast and easy technique for accurate diagnosis of the inferior and lateral walls perfusion defects which will be potentially useful if the final clinical diagnosis cannot be reached.Whereas high false positive result is seen in anterior and septal wall defects with diminished specificity which may need additional other AC methods.