Abstract:To investigate the excystation of metacercaris of Clomorchis sinensis in various alimentary liguids,the freshly taken gastric liguid,duodenal liguid,liguids from the upper,middle and lower parts of small intestine as well as large intestine of rats were taken and used as the excytating liguids to mimic the enviromental condition of intestinal tract,and the excytation of C.sinensis after 30 minutes.If the rate of excytation was less than 10%,the experiment was repeated again,and the time of action was prolonged to 4 hrs with the identical condition as before.The experimental results showed that no excytation occurred in gastic liguid of rats,even the time of action was prolonged to 4 hrs,however,marked excytation occurred after 30 minutes in duodenal liguid,liguid from upper,middle and lower parts of small intestine as well as large intestine of rats with the excytation rate of 97.7%,94.6%,95.9%,9⒈7% and 93.8% respectively,without difference among groups.The excytated metacercaria were all alive.It is evident that the excytation of C.sinesis can occur in various alimentary liguids in 30 minutes except that in gastric liguid.