Dilation of the pupil is a procedure with both clinical and legal ramifications. Optometrists must be familiar with the requirements of informed consent, which must be met when utilizing dilation on the 4-8 percent of patients with anterior chamber angles that are narrow enough to cause an angle closure. Optometrists also must recognize those circumstances under which pupillary dilation is necessary, both for symptomatic and asymptomatic patients. The correct drug regimen must be selected, whether it is for "routine" pupillary dilation or for a patient with a condition requiring a special drug regimen. Patients with dilated pupils must be appropriately managed, and failure to warn a patient of common and expected side effects may create liability if the failure to warn is the cause of injury. If complications--such as acute angle closure--occur, the optometrist must be prepared to manage the situation so as to minimize the risk of injury to the patient.