Abstract Essential oils were obtained by hydro distillation from aerial, seed and root parts of Asystasia gangetica (L) and analyzed for their constituents by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS). Fifty-four compounds were identified in aerial, twenty-one in seed, fifteen in root, respectively which are responsible for 96.80 %, 65.11 % and 78.50 % of oil in each. Aerial is dominated by phthalates (39.00 %), cycloalkanes (28.23 %) and aromatics (17.14 %); the most abundant compounds are toluene (9.12 %), methylcyclohexane (9.02 %) and bis-isodecyloctylphthalate (6.05 %). Others in aerial are branched (6.13 %) and straight chain (3.24 %) alkanes, esters (1.71 %), alcohol (0.72 %), acid (0.36 %), hetero compound (0.27 %), ketone (0.18 %) and terpenoid (0.09 %). Phthalates (24.67 %), alcohols (16.28 %) and straight chain alkanes (8.56 %) are the largest groups in seed oil, with dinonylphthalate (9.40 %), 1-octenol (8.05 %) and methylcyclohexane (6.04 %) as most important. It contains cycloalkanes (6.04 %), aromatics (5.03 %), terpenoid (4.03 %), ester (3.02 %), acid (1.01 %), amide (1.01 %) and branched alkane (0.50 %). Root oil have alcohols (27.32 %), straight chain alkanes (23.61 %) and aldehydes (15.91 %) as the most noticeable, while its dominant compounds are abietal (11.67 %), n-tetracosane (10.08 %) and palustrol (9.02 %). It also has phthalate (5.83 %), aromatics (5.83 %) and cycloalkane (4.24 %). Derivatives of phthalate are obvious in the three oils. There are no aldehyde in aerial; no ketone and aldehyde in seed; no terpenoid, ester, ketone, acid and hetero compounds in root. Notable is the low amount of ubiquitous terpenoids in aerial and seed essential oils, which is absent in root. Volatile composition of Asystasia gangetica (L) is reported for the first time in literature. Keyword: Asystasia gangeticaAcanthaceaeEssential oilsphthalatesalcohols