This study aimed to estimate the degree of body temperature control of the sand dune lizard Liolaemus occipitalis in the subtemperate climate region of southern Brazil. The data suggest more accurate thermoregulation in males than females. Sand substrate appears to be more important than air in serving as a heat source for the lizards. The high conductivity of sand might minimize the effects of the relatively low average air temperatures in southern Brazil. Nevertheless, the mean body temperature of L. occipitalis from southern Brazil was lower than that recorded in northern populations of L. occipitalis and other Liolaemus species in southern latitudes of South America. This suggests that maintenance of body temperature might be the limiting factor for the expansion of the southern limit of the species distribution.