Antagonistic effect of atipamezole (80 micrograms/kg) on medetomidine (20 micrograms/kg)-midazolam (0.3 mg/kg) induced sedation was evaluated in dogs. Atipamezole effectively reversed sedation and significantly shortened arousal time and total recovery time without apparent side effects. Atipamezole also effectively reversed changes in heart rate, respiratory rate and body temperature produced by medetomidine-midazolam. The possible use of atipamezole as a reversal agent might enhance the value and availability of medetomidine-midazolam for a chemical restraint agent in dogs.