A terrestrial orchid, Orchis morio L. is one of the near threatened species in Croatia. Although it inhabits different habitats at a different altitude, a variety of anthropogenic influences, including habitat degradation and transformation, succession caused by the abandonment of traditional management activities (e.g. grazing, mowing) as well as expected climate changes, have been recognized as the most serious threats for its survival. To succeed in a variable environment, O. morio develops specific adaptive responses. We examined 16 morphological and 10 anatomical parameters of O. morio plants growing on two different habitats at a different altitude (steppelike grassland and hilly grassland area) in Northeast Croatia. The results showed that most of the analysed morphological parameters (e.g. plant height, the total number of leaves, the width of the steam below the inflorescence, inflorescence length, total number of flowers), were similar in both study sites while leaf size and anatomy were significantly different. At the hilly grassland area, orchid leaves have significantly larger upper and lower epidermal cells, thicker cuticles and mesophyll layers. In conclusion, changes in morphology and leaf anatomy of O. morio depend on the local environmental conditions, but further investigations are necessary to improve our knowledge about its adaptation strategies and to provide an important base for the effective conservation of this threatened species.