New populations of the Critically Endangered anuran species Alsodes vanzolinii (Donoso-Barros 1974) were discovered during two field surveys at Nahuelbuta Range, Biobío region, southern Chile. Adult specimens have not been reported since the original description of the species heretofore. The new records provided herein extend the latitudinal limit of what was previously thought to be the only population of the species 40 km to the southwest, and the altitudinal limit from 25 m a.s.l. to 700 m a.s.l.