We present the first data of body size and age structure (based on the skeletochronological examination) of Darevskia bithynica from two localities characterised with different altitudes, i.e. Zonguldak (50 m) and Bolu (1200 m). Males from both lowland and highland populations were slightly larger than females. This difference was not significant for the lowland population. The maximum lifespan was found to be six years for both populations. Intersexual differences in snout-vent length were male-biased and this may be linked to the climatic conditions.