Transient vision loss may be a harbinger of a sinister process and typically elicits trepidation among practitioners. It can occur monocularly or binocularly. The tempo of onset as well as the duration of symptoms can be important factors in determining the etiology in various patients. Monocular symptoms suggest disorders of the retina or optic nerve, while binocular disorders suggest intracranial processes. Migraine and papilledema may cause either monocular or binocular symptoms. This chapter will develop a framework for diagnostic testing in the patient with transient vision loss as well as stress the importance of visual field testing or perimetry.Continuum Lifelong Learning Neurol 2009;15(4):85-92.