In the era of high technology and consumer litigations, the disease management has leaped to very high level to nanotechnology and further. As life span of individual human has increased, so are the disease pattern and its natural course. But human anatomy has very few deviations from its basic organogenesis. Identification of disease particularly of vascular origin and in particular of brain vascular pattern is very essential for the management. The present study was an attempt to find out the pattern of circle of Willis among South Indian population.Completeness of circle of Willis and anterior communicating artery as well as anomaly .we have examined 50 brain specimens. In the present study we noted that the normal circle was found only in 72% of brains examined. Among the 28% of variations, 6 were in anterior circulations Among the 6 anterior circulation variation 1 anterior communicating artery was absent, 2 were slender and 1had an oblique course and 1 was absent. The circle was incomplete in 6 specimens. Incomplete circles were associated with migraine aura subjects with controls and is associated with alteration in cerebral blood flow. Careful computed angiographic evaluation and an understanding of the vascular interrelationships in the circle of Willis are essential for a successful postoperative course, especially when very rare vascular anomalies treated.