SUMMARYThe time course of the intraocular hypertensive action of suxamethonium was studied in thirty-four patients who were given this drug under light general anaesthesia induced with thiopentone and maintained with nitrous oxide, oxygen and ether. The tension was measured first during light surgical anaesthesia and in no patient did the initial value exceed the normal upper limit. A rise in tension was manifest within 1 minute of the injection of suxamethonium. The peak action was noted between the second and fourth minutes and had subsided by the sixth minute. Endotracheal intubation following suxamethonium exaggerated the intraocular hypertensive action but did not prolong its duration. The results suggest that the use of suxamethonium to facilitate endotracheal intubation during general anaesthesia for intraocular surgery is safe in patients whose intraocular pressure is within normal limits, provided the anterior chamber is opened more than 6 minutes after intravenous injection of suxamethonium.