The chemical composition of the chloroform extracts of flowers, stems, and roots of Tripleurospermum callosum (Boiss. & Heldr) E. Hossain growing along the northeastern coast of Turkey was studied by gas chromatographymass spectrometry (GC-MS). The GC-MS analyses of the chloroform extracts from air-dried parts of T. callosum yielded the identification of 93 compounds. These compounds were separated into eight classes that were terpenes-terpenoids, hydrocarbons, alcohols, acids, oxygen-containing compounds, steroids, aromatics, and others. Major compounds were moretenol (11.71%) in flower oil: linoleic acid (16.18%), n-hexadecanoic acid (17.88%), and 1-tricosene (13.41%) in stem oil: and n-hexadecanoic acid (6.18%) in root oil. Similarity, of chloroform extracts in flowers, stems, and roots of T. callosum were in the ratio of 13.77%, 45.99%, and 30.16%, respectively. © 2005 Taylor & Francis Ltd.