Heat resistance of muscles and actomyosin proteins was determined at damaging temperatures of 41, 42, and 43 degrees C in three green toad (Bufo viridis complex) populations from different climatic zones of Uzbekistan. The highest muscle and model resistance to these temperatures was revealed in toads living in the warmest plain regions of the country, while the lowest resistance was specific for animals from the piedmont and mountain regions. The variability of heat resistance of the muscle and models was also the highest in toads of the first group. Divergence going in this animal species is proposed.