Trochulus striolatus is a land snail showing great morphometric variation in its shell, which is the basis for recognition of its subspecies. However, this variability can result from an influence of environment. To verify the possible effect of bioclimatic and spatial variables on the shell size and shape, we studied many samples collected from four biotic zones (lowland, submontane, montane and subalpine). Many of its shell features appeared significantly negatively correlated with a precipitation parameter and altitude, whereas positively correlated with temperature parameters. The shells were smaller at higher altitudes and in colder environment with greater precipitation. The reduced growth period can be an adaptive response to the shorter growing season in mountainous regions compared to lowland areas, where the longer season permits a longer growth resulting in larger mean adult body size. This conforms to the converse Bergmann's cline. The synergetic interactions between seasonality, temperature and moisture best explain the size variation in T. striolatus resulting from the influence of local environmental and/or climate factors. Therefore, there is no sufficient justification for subspecies recognition and the subspecific epithets for T. striolatus should be discarded.