Field observations revealed, for the first time, cases of predation on Gordius austrinus by Salmo trutta in Risopatrón Lake, Aysén Region, Chile. Reinvestigation by SEM of the characteristics of the posterior end and of the cuticle of the specimens of horsehair worms collected inside the stomach of brown trout allow us to assign the specimens to the species Gordius austrinus. Also we could show that in some specimens the cuticle of mid body and terminal end presented structural alterations, due to the action of the digestive juices of the fish. This finding implies the extension of the distribution range of G. austrinus.