BACKGROUND: Benign episodic unilateral mydriasis is one cause of anisocoria. This phenomenon is thought to be related to an imbalance between the sympathetic and parasympathetic nervous systems. There is a documented association with migraines, but asymptomatic cases have also been reported. A challenge with all cases is the level of investigation required to exclude more sinister causes of nervous system dysfunction. In a dynamic flight environment, additional considerations need to be made, such as varying light levels and use of night vision devices. CASE REPORT: A 27-yr-old woman on deployment to Afghanistan as a flight nurse presented to the role one clinic with right-sided mydriasis.The patient denied headache or any history of migraines. A dilated right pupil that was reactive to light was found on exam. Symptoms and exam findings resolved shortly after initial presentation. We consulted an ophthalmologist who requested patient transfer for review. He made a diagnosis of benign episodic unilateral mydriasis. DISCUSSION: There are a variety of causes for anisocoria. A thorough history and examination are required to avoid unnecessary investigations that may not be locally available in the more austere deployed military settings. From an operational perspective, the decision needs to be made regarding the maintenance of flight status. Consideration needs to be given to patient care capability when treating a flight nurse. In cases of rapid resolution such as this, removal from operational status is not reasonable should a clinician be confident of the diagnosis.