Summary A new species of nematode, from the family Spiruridae, is described using parasites from the esophageal mucosa of Proechimys roberti (Rodentia: Echimyidae), which were obtained during a fauna survey in the Tapirapé-Aquirí National Forest, Carajás Reserve, Brazil, Eastern Brazilian Amazon. The helminthes were collected from the esophagus, fixed and processed for light microscopy. Spirura carajaensis n. sp. differs from other species in the genus because it has a left spicule with a well-developed sheath, which is leaf-shaped and covers the terminal half of the spicule. Males and females have a small appendix on the caudal end. This structure has not been reported before for this genus. The present study reports the first record of parasitism by Spirura in rodents of the genus Proechimys in Brazil and in the Amazon biome.