Thirty patients received topical application of either timolol ophthalmic solution 0.25%, or normal saline, 2 h before elective ophthalmic surgery in a double-blind study. The responses to suxamethonium and tracheal intubation were compared by measuring intra-ocular pressure before induction of anaesthesia, 1 min after administration of thiopentone 2-4 mg.kg-1, 1 min after administration of suxamethonium 1 mg.kg-1, and 1, 2.5 and 5 min after tracheal intubation. There was no significant difference between the groups.