Recent work in Australia and Africa has shown that heterothermy is widespread among phylogenetically diverse tropical and subtropical mammalian taxa. However, data on the use of heterothermy by Neotropical mammals are relatively scant, and those studies that exist focus on insect-eating bats. We investigated the capacity of fruit-eating Neotropical bats to use heterothermy when exposed to acute cold temperatures, and compared this to previous data focused on insect-eating bats sampled from the same region and time of year. We measured rectal temperatures prior to acute cold exposure (1 hr at an air temperature of 6, 7, or 10°C), and again after exposure. Our data show considerable variation in the thermoregulatory patterns of Neotropical bats, and generally, our results show that smaller bats cool quicker and to a greater extent than larger bats. Our results highlight the importance of energy conservation even in environments in which resources are relatively abundant.