Essential oil composition and Acetylcholinesterase (AChE) inhibition properties of Tripleurospermum inodorum(L.) Sch. Bip. were investigated. Essential oils of flowers, leaves and stems were obtained through hydro-distillationusing a Clevenger type apparatus with 0.03, 0.02 and 0.01% (v/w) yields, respectively. Essential oil composition ofthe oils was determined by GC-MS analyses. Total of ninety compounds were identified in flower oil comprising of80.7% of the essential oil. The main components of the flower oil were artemisia ketone 14.4%, terpinen-4-ol 5.5%,1,8-cineole 5.1%, sabinene 4.7% and tricosane 4.6%. Leaf oil was characterized by 35 compounds representing 62.7%of the oil. Leaf oil contained caryophyllene oxide 16.0%, phytol 12.1%, spathulenol 5.9%, hexahydrofarnesyl acetone3.8% and salvia-4(14)-en-1-one 3.5% compounds with high relative percentages. Stem essential oil comprised oftwenty-eight compounds representing 87.2% of the oil. The main components of the stem essential oil were wereneryl acetate 12.8%, (E)-β-farnesene 12.5%, phytol 12.1%, guaia-6,10(14)-dien-4β-ol 10.8%, γ-cadinol 7.8%, nonacosane7.3%, decanoic acid 6.3% and caryophyllene oxide 4.6%. In vitro AchE inhition of the oils were evaluated by theEllman spectrophotometric method. AChE inhibitory property was investigated for the flower oil with at four differentconcentrations. Highest AChE inhibitory property was observed for 20 mg/mL oil concentration (53.35 ± 1.37 %; n=3). This AChE inhibitory concentration was equivalent to the activity of 1.26 μg galanthamine hydrobromide in theassay. Activity of the essential oil was concentration dependent.