The effect of ketamine on intraocular pressure (IOP) was studied in 10 children. Control IOP values were determined prior to induction of anesthesia, following premedication with atropine alone or in combination with pentobarbital and meperidine. After the IM injection of 8 mg/kg of ketamine, the IOP was determined at 5, 10, 15, and 20 minutes. Mean (+/- SD) IOP values before and after ketamine were 22.2 +/- 4.8 and 16.7 +/- 3.3 torr (p less than 0.001), respectively. The authors believe that the reduction in IOP was not due to ketamine, per se, but rather to lack of patient relaxation and cooperation during control measurements. At the end of 20 minutes, a second dose of ketamine, this time 1 mg/kg IV, was given and measurements were repeated at the same intervals. In 5 patients, the effects on IOP of d-tubocurarine, endotracheal intubation, and N2O inhalation also was evaluated. A significant increase (6.7 torr) in IOP was observed only after endotracheal intubation. The authors conclude that ketamine does not raise IOP in the healthy pediatric patient and, therefore, can be used for ophthalmic procedures requiring sedation or anesthesia.