The antineoplastic activity of numerous Amphipterygium adstringens fractions has been studied on dba mice bearing RC mammary adenocarcinoma. Methods of anticancer evaluation are fully described. Several tumor inhibitors, as well as activators, were found in the various drug fractions. The methanol extract of the whole drug exhibited the most pronounced inhibitory activity. The tumor-damaging capacity of the drug has been shown to be mainly associated with the saponincontaining fractions.