The dry rhizome of Acorus tatarinowii Schott is a common traditional Chinese medicine and could be used for treatment of lots of diseases,such as epilepsy.In this paper,the volatile constituents of Atatarinowii Schott from 4 growing areas,egAnqing,Anhui;Jinhua,Zhejiang;Songxian,Henan and Zhumadian,Henan,were investigated by gas chromatography-mass spectrometry(GC-MS).Total of 45 volatile constituents were tentatively identified and their relative contents were determined.There were 4 common volatile constituents(β asarone,γ asarone,α asarone and cis methylisoeugenol) in Atatarinowii Schott,which occupied more than 1% of the contents of the volatile constituents.Their retention time and relative contents could be regarded as the essential condition of the identification and quality assessment on Atatarinowii Schott.In application of the dividing sections,the total ion current chromatograms of Atatarinowii Schott were divided into 4 sections and were further compared with the relative retention value(α) and the relative peak area(Sr).It was shown that the 3rd section of the total ion current chromatograms was the major active ingredient of Atatarinowii Schott and consisted of the 28th,30th and 36th peaks which corresponded to γ asarone,β asarone and α asarone,respectively.This study provided a new approach for the comparison and quality assessment of Atatarinowii Schott from different growing areas.