Background: The Circle of Willis (CoW) is the primary structure that provides regular blood flow to the brain. It demonstrates a lot of anatomical variants, which have been thought to be affected by age and sex. Objectives: This study aimed to determine the frequency of CoW anatomical variations in an Egyptian population using computerized tomography angiography (CTA). Materials and methods: Retrospective computed tomography (CT) angiography (CTA) study of 100 patients, divided into < 40 and > 40 age groups. 3D images were analyzed after bone removal. CoW morphology was classified based on completeness and potential for collateral flow. Diameters of the vessels were also measured. Results: Significant differences in posterior CoW variations (types "a," "b," "d") between age groups, with higher "a" type frequency in younger patients. Significant differences in anterior CoW variation (type "a") between age groups (p=0.001). Significant difference overall in configuration of the CoW between the two age groups. Significant differences in arterial diameters (RT ICA, Left ICA, Left A1, LT PCOM, RT PCA and LT PCA) were recorded between males and females. Significant differences in arterial diameters were recorded (RT PCOM, LT PCOM, RT PCA and LT PCA) between age groups. Conclusion: In terms of the Egyptian population, there was a great variability of the anatomy of the CoW in asymptomatic subjects. Hence, such anatomic changes have to be considered throughout radiologic interpretation and have to be documented in anatomy text.