Abstract:Objective:The fruit of Chaenomeles lagenaria is acommonly used drug in Chinese traditional medicine. It is especially effective on rheumatism. The current work is to find out the chemical basis of its pharmacological activity.Method:All compounds were extracted with organic solvents and separated by silica gel column or thin layer chromatography,and then purified by recrystalization.The structures were elucidated on the basis of chemical reactions and spectral data analysis.Result:In addition to the compounds reported in our previous work,there triterpenoid compounds were separated and identified as 3-O-acetyl ursolic acid 3-O-acetyl pomolic acid and betulinic acid respectively.Conclusion:It is obvious that triterpenoid compounds are dominant among the chemical constituents of C.lagenaria.But it is still to be clarified whether they are the chemical basis of the drug‘s pharmacological activity.