The effect on intraocular pressure of induction of anesthesia with 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazol[1,5-a][1,4]benzodiazepine (midazolam, Ro 21-3981, Dormicum) as maleate or 7-chloro-1,3-dihydro-1-methyl-5-phenyl-(2H)-1,4-benzodiazepin-2-one (diazepam) has not previously been reported. We induced anesthesia in 30 patients, free of ophthalmologic disease and in good general health, with either midazolam maleate, diazepam or 5-ethyl-5-(1-methylbutyl)-2-thiobarbituric acid (thiopental). Ten patients were treated with each agent for induction. Intraocular pressure was measured with a hand-held Perkins applanation tonometer before induction, 1 and 3 min after induction, 1 min after succinylcholine, 1 mg/kg, and 1 min after tracheal intubation. A significant (p less than 0.001) decrease in intraocular pressure occurred after each induction agent both 1 and 3 min after induction. Also, after each agent, a significant rise in intraocular pressure compared with control occurred after succinylcholine and tracheal intubation. We conclude that midazolam maleate and diazepam reduce intraocular pressure to the same degree as thiopental and would be safe for procedures in which a fall in intraocular pressure is desirable; however, none of these drugs will protect against the rise in intraocular pressure seen following the administration of succinylcholine or tracheal intubation during a rapid sequence induction of general anesthesia.