ABSTRACT High elevation habitats within the Mediterranean biome are expected to be disproportionally exposed to climate change impacts in comparison to the ecosystems of the lower and drier sites. The distribution and structure of alpine ecosystems greatly depend on temperature variables including growing season length. Tree-line shifts, structural change of alpine plant communities and shifts of the alpine-nival ecotone are among the most commonly observed impacts of climate change. The Global Observation Research Initiative in Alpine Environments (GLORIA) network has developed a common methodology and facilitates a global approach for studying the effects of climate change in alpine ecosystems with repeated measurements in permanent plots. Mt Olympus, Greece, was the last target region to join the network. In this study we use the vegetation data from the baseline survey on Mt Olympus to describe floristic patterns along an elevational gradient of four summits. To examine compositional, life-form and chorological differences between- and within-summits we analyzed data from 32 plots. Moreover, we fitted generalized linear models to distinguish important environmental variables for the occurrence of plant taxa. Our results demonstrate that elevation was the dominant factor influencing vegetation changes along the examined gradients. Additional, the life-form spectrum does not provide sufficient information to be used as index for monitoring climate change impacts on vegetation composition. Instead, the use of the species matrix provides enough information regarding the between-summits dissimilarities. We also identified a number of plant taxa that are highly related to either low or high elevations. These taxa could be used as early warning indices of compositional shifts.