ABSTRACT
Ajowan is one of the medicinal plant cultivated in Iran. The Ajowan essential oil is mostly used in food, health and pharmaceutical industries. To determinate the chemical composition of Ajowan essential oil cultivated in Qazvin. Twelve samples of Ajowan seeds were collected from a research farm [Qazvin Agriculture and natural resources research center] in 1381. The essential oil was obtained byhydro-distillation technique and further analyzed by GC and GC/MS for determination of chemical compositions. The content of essential oil in different samples were ranging between 3.1% to3.5%. Nine chemical constituents were indentified. Themol, e-terpinene and p-cemene were the major constituents of oil. Ajowan essential oil produced in Qazvin was mainly composed of thymol [40-45%]