This paper is a narrative review of the literature regarding diagnostic procedures in anisocoria. Due to the many technological and pharmacological advances made in modern day medicine, an accurate diagnosis is sine qua non. Patients displaying acute pupil irregularities are an increased risk for life threating conditions. Workup of acute anisocoria frequently involves costly and/or invasive procedures, which has resulted in much debate over practical guidelines on how to handle abnormal pupillary findings. Nonetheless, there is a body of evidence suggesting that a thorough eye examination results in better overall patient outcomes. Currently, there is a consensus that a clinically guided history and examination is the first step in establishing a diagnosis. Laboratory studies, imaging studies and other diagnostic procedures depend entirely upon the underlying cause of anisocoria. In the hospital setting, physicians are required to rule out life-threating causes. Conversely, in an outpatient setting an underlying etiology must be determined. Anisocoria may be the cause of variable patient morbidity thus reinforcing the value of a prompt diagnosis, effective communication and proper follow up in such patients.