abstract the hydrodistilled essential oil from aerial parts of lychnophora pinaster mart. was analyzed by gc and gc/ms. plants were collected at 3-month intervals in a completely randomized design with six repetitions and the data was analyzed at the level of 5% of probability by tukey's test. there was a significant difference for oil contents in the different seasons. the lowest oil content was obtained in the summer (about 50% inferior to the other seasons). methyl (e)-cinnamate was obtained as the major compound (86-90%) of the 14 identified components. key word index: lychnophora pinaster asteraceaeessential oil compositionseasonal variationmethyl (e)-cinnamate