Background & Aims: The relationship between variations of Willis circle and some cerebrovascular diseases has been shown in previous studies. A few studies have been conducted in Iran on these variations. Methods: This study was performed on 100 recently deceased Iranians due to car accidents who had been referred to Kerman Forensic Medicine Center for autopsy. The length and diameter of cerebral vessels were measured using glass plate method and variations of Willis circle were determined according to Lazort classification. Results: The sample included 81 males and 19 females aged 16-81 years. The two most prevalent forms of Willis circle were type 1 (50%) and type 4 (38%) according to Lazort classification. Asymmetry and hypoplasia were seen in 51% and 61% of cases respectively. Asymmetry was most often seen in the left posterior communication artery. There was no significant relationship between the presence of asymmetry in anterior cerebral arteries and the size of anterior communicating artery. Moreover, the size of the posterior communication artery had not been affected by the presence of asymmetry in the posterior cerebral arteries. Conclusion: However, the anatomical variations found in this study were similar to those in the literature, racial similarities among the studied populations do not allow to exclude the role of race on the variations of Willis circle. The difference between common variations in the cadaver and in vivo studies hypothesizes that radiological studies during life are more appropriate to show the role of race on the variations of the circle of Willis. Nonsignificant relationships between the size of communication arteries and anterior and posterior cerebral arteries support this hypothesis.