Background: Atherosclerosis is a disease of the large and medium-sized arteries causing luminal narrowing (focal or diffuse). Aim of the Work: Measure the relationship between coronary artery disease complexity using SYNTAX score and peripheral arterial disease complexity using TASC II score. Patients and Methods: The study was designed as a prospective single center cross-sectional study conducted at Ain shams university hospitals. The study included 50 patients referred for elective coronary angiography in the time period from August 2016 till July 2017.  Results and conclusion: Patients with complex PAD had complex CAD. This finding suggested that PAD and CHD are different clinical manifestations of atherosclerosis and systemic pan vascular involvement is present in patients with complex lesions. (P-value 0.046).