The investigated Pseudotsuga menziesii (M i r b e l) F r a n c o were grown in two localities, in the urbanized environment of the town of Nitra (locality N) contaminated by immissions from traffic and in the Arboretum Mlynany SAS (locality AM), in the relatively clean environment. The urban environment caused a change in the content and composition of terpenes in needles. In both localities a higher content of terpenes was found in the first-year needles compared with the second-year needles. At the AM the highest number of terpenes was found in August (15 terpenes) while only 7 terpenes were found in the 1st-year needles in the N locality. At the AM locality two terpenes showed the content above 1% during the whole growth season only: alfapinene 2.4-19.2%, bornyl acetate 6.4 - 54.9%, at Nitra there were four terpenes alfa-pinene 10.1-16.7%, camphene 19.4-37.8%, limonene 2.3-3.5%, bornyl acetate 30.1-51.3%. In the N locality, santene, 1.8-cineole and eugenol were missing in the 1st year needles. At Nitra the content of alfa-pinene, camphene and beta-pinene has been significantly increased in needles in comparison with the AM locality. The urban conditions have caused notable changes in the alfa-pinene to beta-pinene, alfa-phelandrene and terpineol ratio in comparison with the relatively clear locality of AM. Terpenes in conifers are significant chemomarkers of environmental impact.