Combined intramuscular administration of ketamine 8mg/kg. xylazine 2mg/kg were done to evaluate effect of anesthesia in Siberian tiger White tiger and Bengal tiger. Mean induction time(MIT), mean arousal time-(MAT). mean walking time(MWT) and clinical sign were evaluated. The results were as follows. MIT were taken 16.1$pm$3.5 minutes for Siberian tiger. 15.5$pm$2.4 minutes for White tiger and 12.3$pm$2.5 minutes for Bengal tiger. MAT were taken 44.2$pm$9.5 minutes for Siberian tiger, 48.3$pm$8.6 minutes for White tiger and 58.7$pm$5.8 minutes for Bengal tiger. MWT were taken 110.6$pm$11.6 minutes for Siberian tiger, 106.7$pm$13.1 minutes for White tiger and 99.6$pm$10.2 minutes for Bengal tiger. Nausea. vomiting. salivation. severe convulsion. sudden decreased respiration and dyspnea were observed in Siberian tiger during sedation and anesthesia. Also, nausea, vomiting, salivation and convulsion were observed in White tiger and Bengal tiger but the clinical signs were more mild than Siberian tiger. The Bengal tiger which used combined ketamine 5mg/kg , xylazine 1mg/kg were shown reduced induction time compare with combined administration ketamine 8mg/kg, xylazine 2mg/kg in Bengal tiger as 10.8$pm$32 minutes for MIT. 32.3$pm$4.3 minutes for MAT and 78.5$pm$7.3 minutes for MWT Vomiting and convulsion were observed during induction time but there were no nausea and salivation. The present results suggested that preventive methods against severe convulsion and dyspnea should be required in Siberian tiger when combined anesthesia of ketamine 8mg/kg, xylazine 2mg/kg used. Combined anesthesia of ketamine 5mg/kg, xylazine 1mg/kg in Bengal tiger might be very effective for simple surgical procedure and diagnosis.