As it is well known the beginning, the course and the result of the cerebral-vasculare disease depends on, among other stuff, the possibility of establishment of the brain collateral circulation. The Willis's artery circle based on brain is the most important anastomoses between the blood circulation of the both, carotid and basilar artery. However, in almost half of the cases of the examined circle of Willis, certain deviations from the normal anatomy configuration have been identified that immensely facilitate occurance of vascular diseases, because it makes difficult establishment of collateral blood circulation. In this particular study, 150 MRI patient's angiographics had been analyzed that were processed at the Radiology Institute of the Clinic Center of the University of Sarajevo. The morphologic variations of the circle of Willis were analyzed on these angiographics and those were patients who did not have any signs of cerebral-vasculare diseases. We have tried to determine which variations are the most commonly occuring in the front segment of the circle of Willis with two target groups (older -- above 60 years old and younger- up to 34 years old) and including both genders. The method of the MR angiography in two projections enabled good visualisation of all components of the circle of Willis and based on their analysis we have achieved the following results. The complete front configuration of the circle of Willis had been found with all patients in 76,7% of the cases. We noted slightly higher percentage of the anterior configuration with younger category of patients compared to older patients, and with males compared to females. Out of the variations that damage the anterior segment of the circle of Willis, the first one, according to the frequency of occuring, is the variation of the type of hypoplasia or aplasia of Al segment of the anterior cerebral artery, and then the variation marked as duplication or multiplication of the anterior communicating artery.