Adult individuals of the calciphilous snail species Helix lutescens collected on road-sides in South Poland, independently from other habitat characteristic (open vs. closed) have a smaller shell size (six measured parameters and total shell-size obtained as PCI in principal component analysis) than the individuals living far from roads. This difference is probably caused by a lead contamination in plants and next by its impact on a snail calcium metabolism. Helix lutescens and especially its shell size can be used as a suitable bioindicator for measuring pollution effects.