Brain sizes vary substantially across vertebrate taxa yet the evolution of brain size appears tightly linked to the evolution of life histories. For example, larger-brained species generally live longer than smaller-brained species. A larger brain requires more time to grow and develop at a cost of exceeded gestation period and delayed weaning age. The cost of slower development may be compensated by better homeostasis control and increased cognitive abilities, both of which should increase survival probabilities and hence lifespan. To date this relationship between lifespan and brain size seems well established in homoeothermic animals, especially in mammals. Whether this pattern occurs also in other clades of vertebrates remains enigmatic. Here, we undertake the first comparative test of the relationship between lifespan and brain size in an ectothermic vertebrate group, the anuran amphibians. After controlling for the effects of shared ancestry and body size, we find a positive correlation between brain mass, age at sexual maturation, and lifespan, across 40 species of frogs. Moreover, we also find that the ventral brain regions, including the olfactory bulbs, are larger in long-lived species. Our results indicate that the relationship between life history and brain evolution follows a general pattern across vertebrate clades.