A generic composition and the spatial patterns of the Ephemeroptera community present in the Guacharos National Natural park, municipality of Palestina, deparment of Huila is given. Fieldwork was carried out in three streams between october 2003 and september of 2004. The immature stages were collected with Thienneman's net on substrates such as rocks, stones, mosses and packs of decaying leaves. These aquatic Systems show poor organic matter conteni and low levels of conductivity, alkalinity and hardness. The Ephemeroptera community consists of eleven genera belonging to five families. The most important genera collected were Baetodes, Prebaetodes y Thraulodes.