The assimilation efficiency of Bufo spinulosus tadpoles from four localities in Chile was evaluated for two different temperatures (15 and 25 ºC) and two different diets (low nutritional quality diet (LQD): 22.28 mg g N-1; high nutritional quality diet (HQD): 47.53 mg g N-1) using ash as a marker of digestion. Results showed that geographic origin did not affect assimilation efficiency, while the relationship observed between temperature and diet quality was significant. Assimilation efficiency was greater for the HQD when tadpoles were maintained at 15 °C, instead significant differences were not found between diets for tadpoles maintained at 25 °C. Our results suggest that the effect of temperature on digestive processes is more relevant than its effect on transit time in the digestive tract. The differences in size at metamorphosis in B spinulosus populations of distinct geographic origin could not be explained by the existence of differences in physiologic digestive capacities