One hundred and three patients with strabismus who were undergoing extraocular muscle surgery were studied to compare the incidence of arrhythmia following the traction of ex- traocular muscles under halothane and sevoflurane anesthesia. Fifty four patients were anesthetized with O2-halothane(halothane group) and forty nine patients with O2-sevoflurane (sevoflurane group). The incidences of arrhythmia were 74.1% and 71.4% in halothane and sevoflurane group, respectively. There was no significant change of blood pressure in either group when arrhythmia occurred. The incidence of arrhythmias in female patients of the sevoflurane group was higher than that in male patients, while not in the halothane group. In the sevoflurane group, the incidence of arrhythmia followed by the traction of medial rectus muscle was significantly higher than that of lateral rectus muscle. In conclusion, there was no significant difference in the incidence of arrhythmia following the traction of extraocular muscles between halothane and sevoflurane anesthesia, and sinus bradycardia was the most common arrhythmia with either anesthetic.