A revision of Plectocynipinae was initiated following the recent collections of specimens of Plectocynips Diaz and Araucocynips, new genus, from Chile. In addition to a redescription of the subfamily, we provide redescriptions, based on females, of the species of both genera. Descriptions are provided for Araucocynips ariasae, new species, Araucocynips queulensis, new species, and Plectocynips lago, new species, all from Chile. New host records are provided for Plectocynips pilosus Ros-Farré from galls of Aditrochus fagicolus Rübsaamen and Aditrochus coihuensis Ovruski (Hymenoptera: Chalcidoidea) on Nothofagus pumilio (Poepp. & Endl.) Krasser and Nothofagus dombeyi (Mirb.), respectively. In addition, males are described for Araucocynips ariasae, Araucocynips queulensis, and Plectocynips pilosus.