The following species of rusts parasitic on Cyperaceae H Argentina are studied in. this paper. There are: Puccinia conclusa, P. canaliculata, P. improvisa, nov. sp., P. cyperi, P. heteromorpha on Cyperus spp., P. dioica, P. caricina, P. joerstadiana, nov. sp., on Carex spp,, P. angustatoides, Uromyces correntinum on Rhynchospora spp., and P. liberta and Uredo heleocharidicola on Heleocharis spp.