The mosses are represented by approximately 25,000 taxa worldwide 1,2. Literature review on the chemistry of mosses mentioned the absence or trace amount of terpenoid compounds but, later investigations showed the occurrences of a great variety of terpenes and, other volitale compounds 3-8. In Turkey, the genus Neckera is represented by 5 taxa 1,2. To our knowledge, there is no previous report on the composition of the essential oil analysis and antimicrobial activities of N. complanata and N. crispa. The volatile constituents of the fresh mosses were obtained by hydrodistillation method in a modified Clevengertype apparatus. The obtained crude essential oils were then investigated by GC and GC-MS technique 6-17. EXPERIMENTAL Neckera complanata (Hedw.) Huebener was collected from Sevinç village, Maçka, Trabzon, Turkey (at a height of 315 m) in May 2011. Neckera crispa Hedw. was collected on the stony place in the forest from Zigana mountain, Trabzon-Turkey (at a height of 1509 m) in May 2011. The mosses were authenticated immediately after collection 1,2. Voucher specimens