Data on Brazilian cave psocids (Insecta) of the families Psyllipsocidae and Prionoglarididae are summarized, as a synthesis of the results of the most important investigation on cave psocids ever realized. Prionoglarididae are represented by 4 species of the endemic cavernicolous genus Neotrogla, Psyllipsocidae by 17 species of Psyllipsocus (15 of them endemic) and 2 widely distributed species of Psocathropos. These 19 recently described Brazilian endemic Neotrogla and Psyllipsocus were discovered in the course of the project, based on the examination of about 400 adult psyllipsocids and prionoglaridids collected in 124 caves situated in 59 municipalities and 13 Brazilian states. Some augmentations to the descriptions of the widely distributed Psyllipsocus ramburii, Psyllipsocus yucatan, Psocathropos lachlani and Psocathropos pilipennis are given and the following new synonymies are proposed: Psyllipsocus ramburii Selys-Longchamps (P. variabilis Badonnel n. syn., P. dubius Badonnel n. syn.), Psyllipsocus yucatan Gurney (P. collarti Badonnel n. syn., P. decui Badonnel n. syn.), Psocathropos lachlani Ribaga (Vulturops termitorum Townsend n. syn., Dorypteryx astizi Brèthes n. syn.). The distribution of the 23 species of psyllipsocids and prionoglaridids known from Brazilian caves is analysed and some evolutionary aspects are discussed. A key to the 25 South American species of these families is given, including two other previously known species: Psyllipsocus delamarei from Argentina and the troglobitic prionoglaridid Speleopsocus chimanta from Venezuela.