The biodiversity of the entire planet is threatened by global warming, and among vertebrates, Amphibia is the taxon most negatively affected by this problem. Amphibians depend on an external heat source to achieve and maintain an adequate body temperature, which has a significant impact on their fitness. Therefore, an increase in the average environmental temperature will affect, probably in a negative way, the general performance of amphibians. This makes it imperative to increase our scarce knowledge of amphibian thermoregulation. The aim of this work is to contribute to the knowledge of amphibian thermoregulation by studying the winter thermal ecology of one of the most widely distributed species in Chile, Pleurodema thaul. Individuals were collected during the mid-austral winter in Península de Hualpén, which corresponds to the midpoint of the latitudinal range of distribution of P. thaul. In the field and laboratory we recorded body temperature and the substrate and air temperatures. The data indicate that P. thaul is a thermoconformer, as its body temperature varies during the day, following the temperature of the substrate and the air. Pleurodema thaul does not seem to use morphological body properties to facilitate thermoregulation; body temperature was unrelated to the body size or weight of individuals. The fact that during winter P. thaul does not thermoregulate actively constitutes a clear indication that the global warming may have serious effects on this species.