AIM:To explore the influence of exogenous hydrogen sulfide ( H2 S) on coagulation and fibrinoly-sis in ferric chloride ( FeCl3 )-induced mouse carotid artery thrombosis .METHODS: The mice were divided into sham control group, model group, different concentrations (12.5, 25 and 50μmol/kg) of sodium hydrosulfide (NaHS, H2S do-nor) groups and 30 mg/kg clopidogrel ( positive control ) group.Intraperitoneal injection of NaHS at different concentra-tions and oral administration of clopidogrel bisulfate were performed for 3 d prior to FeCl 3-induced carotid artery thrombo-sis.The frozen sections of the carotid artery were collected to perform HE staining , and the thrombus pattern and the chan-ges of vascular pathology were observed .The thrombus was weighed to calculate thrombosis inhibitory rate .Prothrombin time ( PT) , activated partial thromboplastin time ( APTT) , fibrinogen ( FIB) and fibrinogen degradation product ( FDP) in the mice were also measured by a coagulometer .The plasma levels of thromboxane B 2 ( TXB2 ) , 6-keto-prostaglandin F 1α(6-keto-PGF1α) and plasminogen activator inhibitor (PAI) were detected by ELISA.RESULTS: Compared with model group, NaHS dose-dependently inhibited the formation of carotid artery thrombus .NaHS treatment reduced the contents of TXB2 and PAI, and recovered 6-keto-PGF1αcontent in thrombosis model group .In NaHS treatment groups , 6-keto-PGF1α/TXB2 and thrombus weight was negatively correlated .NaHS treatment prolonged PT and APTT , reduced the content of FIB, but increased the level of FDP in thrombosis model group .CONCLUSION:Hydrogen sulfide prevents FeCl 3-induced carotid artery thrombosis by inhibiting coagulation and activating fibrinolysis .