The dipsadid snake genus Tropidodryas consists of two species that occur in the Atlantic Forest along Brazil’s eastern coast, a conservation hot spot. Life-history information on pairs of sister species might allow insights into the evolutionary transitions that have occurred since the cladogenesis that putatively gave rise to them. We provide information on distribution, morphology, diet, reproduction, and seasonal activity of these species based on the examination of 624 specimens. The genus Tropidodryas occurs along a large extent of the Atlantic Forest of eastern Brazil, with T. striaticeps occurring at higher elevations, on average, than T. serra. These snakes forage by day either on the ground or in vegetation, consuming a wide variety of vertebrates, mainly mammals. Higher proportions of birds in the diet of T. serra and certain mammals in the diet of T. striaticeps probably reflect elevational differences in prey availability. An ontogenetic diet shift occurs in both species, with juveniles consuming mainly ectothermic prey (lizards and anurans), and adults preying predominantly on mammals. Caudal luring has been documented in juveniles, but the pale color and high frequency of injuries on the tail of larger individuals indicate that adult T. striaticeps also employ this technique to attract prey. Sexual dimorphism occurs in body size, tail size, and diameter of the eye. Female reproductive cycles are seasonal in both species, with egg laying occurring in warmer periods of the year. However, T. striaticeps seems to have a more extended reproductive cycle, with some females being able to lay eggs 1 or 2 mo earlier. Environmental differences between high and low altitudes in the Atlantic Forest are likely responsible for the slight ecological divergence between these two closely related snakes.