Lygaeoidea fauna of Puerto Rico and its adjacent islands is presented as part of a revision of the Heteroptera of these islands. In this work, we present 73 species in nine families known from Puerto Rico: Berytidae (4); Lygaeidae (17); Cimidae (1); Ninidae (1); Blissidae (3); Geocoridae (7); Oxycarenidae (1); Pachygronthidae (2); and Rhyparochromidae (37). Of this total, nine represent new records for Puerto Rico: Gampsocoris decorus (Uhler), Spilostethus pandurus (Scopoli), Icshnodemus variegatus (Signoret), Geocoris uliginosus Say, Valtissius distinctus (Distant), Pseudopachybrachius concepcioni Zheng & Slater, Paromius dohrnii (Guérin-Méneville), Ozophora barbudensis Baranowski, and O. xancthocnemis Baranowski. Most species found here are also widely found in the West Indies. The genera with the most species represented are the rhyparochromids Ozophora Uhler and Neopamera Harrington. Taxonomic accounts presented in this work include synonymies, known distribution, lists of hosts and a listing of examined specimens. Also, we provided taxonomic keys and color plates of 52 of the species discussed.