Hysterothylacium winteri sp. n. (Nematoda: Anisakidae) was collected from the intestine of a marine-estuarine fish, Eleginops maclovinus (Valenciennes) (Perciformes: Eleginopsidae), from Abtao in the Gulf of Ancud, Chile. Sixteen (51.6%) out of 31 fish were infected; the intensity was 1-10 (mean 4) worms/host. The new species belongs to the group of congeners possessing one double pair of postanal papillae. By possessing a lateral pair of phasmids situated near the tip of tail, H. winteri most closely resembles Hysterothylacium habena. The new species can be distinguished by the lip flanges forming broadly rounded points and the equal, short spicules (320-400 µm long) representing 0.9-1.7% of body length.