We investigated age structure, body size and longevity in two breeding populations of Darevskia clarkorum inhabiting altitudes ranging from 450 m a.s.l. (Kamilet) to 2250 m a.s.l. (Basyayla) in Turkey by skeletochronology performed on the phalanges. The mean age was found to be 6 years in the Kamilet population and 7 years in the Basyayla population. The maximum life span was 10 years in the lowland population while it was 12 years in the highland population. Age at sexual maturity of both males and females was 1-2 years in the lowland population while it was 2-3 for both sexes in the highland population. Both age and SVL of specimens from the Kamilet population were significantly different between the sexes while age and SVL did not differ significantly between the sexes in Ba, syayla population. As a conclusion, we observed that the mean age, longevity and age at maturity were increased by altitude while there was a decrease based on the mean SVL in the highland population of D. clarkorum. Our data on body size, longevity and age at sexual maturity may contribute to conservation efforts for this endangered species.