Background: Previous studies detected large number of variations in circle of Willis in normal populations. There is limited data for the effect and correlation of normal varieties and pathologic vascular anomalies Purpose: Prevalence of normal variants and impact of its presence in decision making process. Patients and methods: Ninety patients' records underwent therapeutic angiography were retrospectively reviewed and reallocated into two equal groups according to pathology (group 1=vascular malformation group, group 2= ischemic insults). Age, sex, type of pathology, site of normal variants and finally their impact on decision making process were calculated