In the embryonic period, several developmental anomalies of the cerebral arteries occur. The knowledge of these anatomic variations of the cerebral artery is important to avoid the unnecessary surgery and to undergo surgery or interventional radiology with safety. We reviewed 3000 MR angiographies and 700 cerebral angiographies of the previous 5 years to assess cerebral arterial system, and to illustrate the embryological development, imaging findings, occurrence, and clinical significance of the anatomic variation of the cerebral arteries. The normal development and variations of the cerebral arteries are depicted. Knowledge of the anatomic variations is important since it can influence surgical and interventional procedure.