Selection of breeding habitat plays a fundamental role in the reproductive success of urodeles and anurans. We studied the influence of water chemistry variables on the selection of a specific water resource as breeding habitat in Mertensiella caucasica. To determine the influence of water chemistry parameters on their habitat selection, we surveyed a total of 45 small river, streams and brooks in the Western Lesser Caucasus (northeastern Turkey and southwestern Georgia). The water samples taken from these localities were analyzed for 14 chemical variables and the results submitted to multiple logistic regression analysis in order to evaluate the influence of these parameters on the presence or absence of the species in the localities. Of these parameters, chloride concentration influenced the breeding habitat selection of Mertensiella caucasica significantly. To cite this article: F. Sayim et al., C. R. Biologies 332 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.