Philodryas chamissonis, maximum length ca. 2.2 m, feeds on anurans, lizards, birds, rodents, and rabbits; constriction is used for killing endothermic prey. An ontogenetic dietary shift is demonstrated by smaller individuals eating only ectothermic prey. Tachymenis chilensis, maximum length ca. 0.7 m, feeds only on anurans and lizards and does not exhibit an ontogentic dietary shift. Both species are diurnal hunters and typically swallow prey head-first. Prey/predator mass ratios are not especially large compared to other snakes. There is widespread sympatry and considerable overlap in diet, but T. chilensis eats more anurans and extends into cooler, moister habitats than does P. chamissonis. The low species richness of snakes in Chile appears to result from geographic isolation rather than ecological limits on interspecific coexistence.