Eustrongylides uses piscivorous birds as definitive hosts, oligoquets as intermediate hosts and fish as second intermediate hosts. However, amphibians and reptiles can act as secondary or paratenic hosts. The following work presents the first record of Eustrongylides larvae in snakes in the Neotropics. The coelomic cavity of 101 snakes belonging to Helicops infrataeniatus, Philodryas aestiva, Philodryas olfersii, Philodryas patagoniensis, Erythrolamprus poecilogyrus, Erythrolamprus jaegeri, Atractus reticulatus, Dipsas ventrimaculatus, Thamnodynastes strigatus, Phalotris lemniscatus and Bothrops alternatus from southern Brazil were examined. Six H. infrataeniatus were parasitized with larvae of Eustrongylides sp. The encounter of these larvae only in this specie can be related to the aquatic habit of the snake, which allows ecological interactions with the definitive and intermediate hosts of the Eustrongylides cycle. The occurrence of these parasites in a Neotropical snake is registered for the first time, contributing to the knowledge of the helminth diversity associated to Brazilian snakes.Asociación Herpetológica Argentina