South American Trichogrammatidae are poorly known. In this paper we describe a new species of Trichogramma and two new species of Uscana from Chile. The Trichogramma species belongs to the perkinsi group and parasitizes the eggs of Rhyacionia buoliana (Lepidoptera: Tortricidae). One Uscana species belongs to the senex group (new name proposed for the B group) and parasitizes eggs of Pseudopachymerina spinipes (Coleoptera: Bruchidae), and the other Uscana species belongs to the fumipennis group (new name proposed for the C group) and parasitizes eggs of Bruchus pisorum (Coleoptera: Bruchidae). These new species might be useful in biological control, especially against R. buoliana and B. pisorum, important pests of pines and peas, respectively, in Chile.