In order to investigate sedative action of detomidine and its effect on physical signs, hematological and blood chemical components, 15 Holstein cattle were used. The dosage of detomidine was 25 ${mu}$g/kg and 50 ${mu}$g/kg. Blood was collected before injection, 30, 60 and 120 min. after injection. Induction time of sedation in a cattle given with 25 ${mu}$g/kg and 50 ${mu}$g/kg of detomidine was 10.6${pm}$2.8. 7.6${pm}$1.0min. respectively and maintenance time was 70.4${pm}$8.3, 86.5${pm}$9.9, respectively. After injection of detomidine, body temperature was slightly increased, heart rate and respiratory rate were slightly decreased. The levels of red blood cell, hemoglobin, packed cell volume and white blood cell were not changed by detomidine. Blood glucose level following detomidine was markedly increased but total protein, serum glutamic oxaloacetic transminase, alkaline phosphatase, lactic dehydrogenase, blood urea nitrogen and creatinine were not changed. This results indicated that detomidine was useful sedative in bovine practice.