In 100 adult patients undergoing ophthalmic surgery under halothane or enflurane anaesthesia, the electrocardiogram was recorded on magnetic tape and analyzed subsequently for arrhythmias using a high-speed analyzer. Enflurane induced a much less premature atrial contractions (kappa 2 = 4.75; p less than 0.05) and a nodal rhythms (kappa 2 = 4.39; p less than 0.05) than halothane. There were no significant differences between the two drugs in the frequency of premature ventricular contractions and wandering pace maker. Our results confirm those of previous studies during oral surgery that enflurane produced significantly fewer arrhythmias than halothane. The lower incidence of cardiac dysrhythmias and the preservation of cardiovascular stability suggest that enflurane may be the agent of choice for this kind of surgery.