Three novel records of carbon and nitrogen isotopes are presented from two open-air funerary contexts in the interior of the North Patagonian forest. The human samples analyzed confirm the usefulness of the technique to differentiate terrestrial diets from human populations in the Andean area of Patagonia. The results reflect the importance of the forest and its resources in the last millennium, strengthening the models suggesting human populations regularly and permanently exploiting the forest and its resources in the eastern Andean region of northern Patagonia.