Abstract: OBJECTIVE To investigate the antitussive and expectorant effect of garlic oil on experimental mice. METHODS Corn oil was used to dilute garlic oil, and intragastric administration high(100 mg?kg^-1), middle(50 mg?kg^-1) and low(25 mg?kg^-1) doses of garlic oil on mice. Then antitussive test was observed on mice with cough induced by ammonia water, and tissue slicing and HE staining were made to observe structure changes of tracheal tissue in each group. A phenol red excretion test was used to investigate the expectorant effect of garlic oil in mice. Dextromethorphan hydrobromide(10 mL?kg^-1) and ambroxol hydrochloride syrup 4 mL?kg^-1 were adopted for positive drug control. RESULTS Garlic oil was significantly effective on mice with cough(P<0.05 or 0.01). There was an obvious dose-response relationship in the antitussive and expectorant effects of garlic oil in comparison with model group. In addition, garlic oil inhibited inflammatory reaction, congestion and mucous secretion in tunica mucosa tracheae. Moreover, garlic oil had better pharmacological actions than dextromethorphan hydrobromide. CONCLUSION Garlic oil has significant antitussive, expectorant and tracheal mucosal protection efficacy.