Marchantia hexaptera Reich. is a liverwort species, which is endemic to French Polynesia, where it occurs on the islands of Tahiti and Moorea. The major purpose of this study was to compare the compositions of the volatiles present in Tahitian M. hexaptera populations, to determine the chemical homogeneity within the species. This the first study of the chemistry and chemical variation within any species of Marchantia from the Pacific region. GC/MS analysis of 10 specimens collected in Mt. Marau area showed some differences between samples, indicating the existence of chemical polymorphism. Based on the differences in chemical profiles, three chemotypes of Tahitian M. hexaptera were recognized. Chemotype I produces germacrane-type sesquiterpene alcohol, 1(10),4-germacradien-6α-ol, which seems to be good chemical marker of this species. The cuparane-type sesquiterpene alcohol, cyclopropanecuparenol is characteristic for Chemotype II, while the presence of the huge amount of an unidentified sesquiterpenoid, 222 [M] + , 82 (100), 67 (60) is characteristic for Chemotype III. The volatiles composition of specimens belonging to Chemotype II is very similar to that of the Japanese and European M. polymorpha L. The recognized chemical differences were not related to altitude. The chemotypes can occur in the same or overlapping areas. These results were further supported by principal components analysis (PCA) and cluster analysis (CA).