the essential oil (eo) content and composition of tansy (tanacetum vulgare l.) were studied under foliar application of salicylic acid (sa) and orthophosphoric acid (p). gas chromatography (gc) and gas chromatography-mass spectrometry (gc-ms) were employed to determine the chemical composition of eos from the plant. different concentrations of sa (0, 150, 300, and 450 ppm) and p (0, 0.1, 0.15, and 0.2%) were applied to the plant at different stages of growth including vegetative, floral budding, and full flowering. based on the results, sa, p and sa x p significantly (p <= 0.05) affected the eo content and chemical composition of the plant. the eo contents (w/w %) ranged from 0.65% to 1%. the total of 29-37 components were identified in the eo samples. the major eo compounds under different sa, p, and sa x p treatments were camphene (0.6-6.2%), sabinene (0.4-6.1%), camphor (4.2-30.4%), trans-thujone (2.4-54%), trans-chrysanthenyl acetate (0.8-52.1%) and germacrene d (2.9-5.7%).