Introduction: This study concerns some aspects of individual anatomical variability on cerebral vascularisation, particularly arterial circle of Willis. In polymorphism it is important to know the arterial ring once deficiencies in brain may alter pounds. Objectives: The criteria have guided us in making this research as: literature review with reference to the concerned issue; determination of morphometric parameters of the polygon forming arterial vessels; investigate parameters that brain arteries often show polymorphisms location; establish individual anatomical variations of the arterial polygon and arguing their clinical importance. Materials and methods: The work is based on 12 prepared anatomical researches and 18 digitized scientific angiography (DSA). Results: According to the data from the record investigated preparations we found that: In 9 cases the components of the arterial circle of Willis are integral; in 7 cases there was noticed an absence of the posterior artery; in 6 cases it turns out that one of posterior cerebral artery manifests independence and it is not related to basilar trunk; in 4 cases one of the cerebral arteries is atrophied, in counterpart to the second that is being developed to excess; in one singular case independence of the both was registered; in 3 cases the absence of the posterior cerebral arteries, previous cerebral artery were registered. These variations are not considered as pathological if there is a congenital issue, and the perfusion is assured. This cannot be said about the postnatal manifestation, as it may cause the dysfunction of the cerebral vascularisation cycle. Conclusions: As a final overview, referring to the basic form of the arterial circle of Willis we may notice that it opens symmetrically where the communicating and cerebral arteries derive from previous internal carotid artery and posterior cerebral artery is the termination branches of the basilar artery. Willis arterial polygon can be opened unilateral in case of the absence of posterior communicating artery, as well as in the case when the posterior cerebral artery originates from the internal carotid artery. In rare cases arterial circle of Willis may be opened in the anterior section in the case of the absence of the anterior cerebral artery. As well different versions are often met to individual constituents that are having the arterial circle of Willis in the form of aplasia, hypoplasia, hyperplasia and other forms of branching of the arterial circle components, including the atypical formation.