the essential oil of cyclospermum leptophyllum (pers.) sprague ex britton and p. wilson syn. apium leptophyllum (pers.) f. muell. ex benth., family apiaceae (umbellifereae), was analysed by gc and gc-ms. the essential oil showed the presence of thymohydroquinone dimethyl ether (50.7%), thymol methyl ether (11.2%), -terpinene (10.4%), p-cymene (9.5%) and carvacrol methyl ether (5.9%), along with trans-ocimene, -pinene, germacrene d, cumin aldehyde, -humulene, -myrcene, sabinene, limonene, -phellandrene, caryophyllene oxide, -pinene and -thujene as minor constituents. to the best of our knowledge, this is the first study of the essential oil composition of c. leptophyllum collected from india.