Background: The COW shows vast variations in different individuals. The aim of this study was to evaluate and describe the prevalence and patterns of arterial variants and the different morphological variations of the COW on MRA in adult Pakistanis. Aim: To find the different anatomical variations of Circle of Willis in adult patients on magnetic resonance angiography. Methodology: In this descriptive study a total of 90 patients with ages 20-90 years, were selected for the study between July 2021 till October 2021. The adult patients were referred for screening MRA brain in the Department of Radiology. The protocol selected to visualize the COW was 3D-TOF MRA. Results: Data analysis demonstrates that out of total 90 patients, 51(56.7%) were males and 39(43.3%) were females. Overall, 66(79.5%) circles were complete in anatomical configuration and 24(20.5) were incomplete. The anterior circle was complete in 73(81.1%) subjects and incomplete in 17(18.9%) subjects. The posterior circle was complete in 83(92.2%) subjects and incomplete in 7(7.8%) subjects.The most common variation of COW was hypoplasia/absence of segments of Circle of Willis. ACA was the most frequent segment of Circle of Willis that was hypoplastic/absent followed by A1 segment of right ACA is absent in 6(7.2%) subjects and A1segment of right ACA is hypoplastic in 6(7.2%) subjects. Conclusion: The study concludes that mostly the COW is complete in Pakistani adults. There are variations particularly in anterior part as compared to the posterior part of the COW. The most common variants are of A1 segment of Right ACA as compared to other type of variants. Keywords: Circle of Willis, 3D-TOF-MRA, Anterior circulation, Posterior circulation, Complete circle, Incomplete circle,