We evaluated the influence of sex and environmental temperature on thermoregulation by Aspidoscelis calidipes from Apatzingán, Mexico. Range of body temperature was 32.6–44.6°C with a mean (±1 SD) of 40.44 ± 2.55°C, which is one of the highest recorded for the genus Aspidoscelis. Body temperature did not vary as a function of sex and was strongly associated with environmental temperature (temperature of air and substrate) which may be due to territoriality.