The hydro-distilled essential oils obtained from the different organs (roots, leaves, stalks, inflorescences and fruits) of Kelussia odoratissima, an endemic medicinal plant of Iran, were analyzed by gas chromatographyâflame ionization detector (GCâFID) and GCâmass spectrometry (GCâMS) to determine their chemical composition. The essential oil content (w/w%) was in the order of: fruit (1.4%) > root (1.05%) > stalk (0.37%) > leaf (0.27%) > inflorescence (0.2%). The total number of compounds identified and quantified were thirty-two in roots, thirty-one in stalks, twenty-one in leaves, twenty-one in inflorescences and six in fruits, representing 99.5%, 99.2%, 98.2%, 98.1% and 99.7% of the total oil, respectively. The phthalide (Z)-ligustilide (54.0â86.0%) and (2E)-decen-1-ol (2.0â12.3%) were the major compounds in all plant organs. These results suggest that the five studied organs of K. odoratissima are potentially good sources of phthalides, which are known for their anti-inflammatory, anti-tumor and insecticidal properties. This is the first report on the essential oil composition profile in the full range of organs of this species.