Anatomic variations and anomalies in the arteries from the circle of Willis or the heart are common, sometimes even more common than the classic morphology. There is no reference in the literature to a correlation between variations and anomalies in these two organs. Coronaries and circle of Willis from 50 cadavers were dissected and analyzed. Eight percent presented a left dominant pattern of heart circulation, 4% were undetermined, and 88% were right dominant. Eighteen percent presented significant anomalies in the posterior circulation of the circle of Willis. The posterior cerebral artery originated from the internal carotid artery on the left in 2%, on the right in 12%, and on both sides in 4% of the cases. For every case that presented a left coronary dominant pattern, there was a concomitant anomaly in the posterior cerebral circulation (p = 0.0006). However, there is still no explanation for this finding.