Characteristics of the meristic features of the external morphology of young and adult snakes (the Colubridae family) of three species, namely, the grass snake Natrix natrix, the dice snake N. tessellata and the Pallas’ coluber Elaphe dione, living in the Samara region, are described. For the first time, a comparative analysis was carried out of a number of morphological characters of uneven-aged snakes, namely: newborns obtained in laboratory conditions, juvenile specimens, and adult snakes captured in nature. It was revealed that those morphological features which remained unchanged during the snake's life (the number of Ventr., Scd., Lab. and Temp. scales) significantly differred in specimens of laboratory and natural origin. Statistically significant differences were also found between young and adult specimens of the dice snake from nature.