Background & Aim:Mentha longifolia (L.) Huds is an aromatic perennial herb that belongs to the family Lamiaceae. The aim of this study was to identify chemical composition of aerial parts (including leaf, stem and flowers) of M. longifolia collected from (Kamu mountain) Isfahan province. Experimental: The essential oils were extracted using the hydrodistillation method and analysed by GC-MS. Results: The essential oil yields obtained from the aerial parts of M. Longifolia were1.34, 0.76 and 0.97 ml/100 g dry matter in leaf, stem and flowers, respectively. Results indicated significant differences (p < 0.01) among the aerial parts for the main constituents in the essential oil. The major constituents of the leaf oil were 1,8-cineole (37.16%), piperitenone oxide (18.97%), sabinene (13.94%), α-pinene (8.92%) and pulegone (6.14%). The major constituents of the stem oil were 1,8-cineole (36.81%), pulegone (18.61%), piperitenone oxide (12.21%), sabinene (7.05%) and the major constituents of the flower oil were piperitenone oxide (37.67%), 1,8-cineole (23.02%), sabinene (13.56%) and α-pinene (10.45%).Recommended applications/industries: Differences in the volatile composition of the plant material could be attributed to the growth and cultivation conditions of the plant, to the methods of extraction and to the harvesting time. تفاصيل المقالة