:This study was conducted to analyze the results of inhalation anesthesia performed at the equine hospital of Korea Racing Authority (KRA) and to find out the influencing factors on mortality during and/or after inhalation anesthesia. Among 585 cases of anesthesia, orthopedic surgery (410) was performed the most frequently, followed by colic surgery (85) and upper airway surgery (45). Twenty out of 585 horses were either euthanized or died during and/or after anesthesia. Among those twenty horses, fourteen horses received colic surgery, three received orthopedic surgery, and three others received upper airway surgery. The major causes of mortality were rupture of intestine in colic surgery and airway obstruction during recovery in upper airway surgery. Myopathy, refracture, laminitis were the causes of mortality in orthopedic surgery. Consequently, the horses that received colic and upper airway surgeries showed significantly high mortality rate rather than horses that received orthopedic surgery (p < 0.01). According to the results, horses that received colic surgery showed the highest mortality rate from euthanasia due to poor and grave prognosis. To reduce the perioperative mortality of horses, it is recommended to perform perioperative intensive care for colic surgery and careful monitoring for upper airway surgery during recovery.