Diplomystidae is well known as the oldest catfish family in the order Siluriformes. In Chile three of the six described species are present (genus Dyplomystes), distributed allopatrically in rivers from the Rapel Basin to the Valdivia Basin (34 degrees S - 40 degrees S), and some isolated populations of unidentified diplomystids in the Baker Basin (47 degrees S). In this study we analyze the stomach content of individuals of Diplomystes from all hydrological drainages in which populations are currently present in Chile, including the Baker River. A total of 175 individuals were analyzed from which 90.3% were juveniles. Results show that, regardless of the provenance of individuals analyzed, larvae of the insect family Chironomidae were the most consumed item. The only exception occurred in the Tolten Basin, whose population consumed mostly larvae of the insect family Simulidae. No marked differences were found between the diet of juveniles and adults, except for the presence of crustaceans of the genus Aegla in adults. These results confirm a carnivore and generalist diet for the genus Diplomystes, with no changes along the latitudinal gradient in Chile.