The aim of this work was to study the degradation and detoxification of three textile azo dyes (Reactive Red 198, Reactive Red 141 and Reactive Blue 214) by mixed fungal cultures from semi-arid region of Brazilian Northeast. Sediment samples of twenty water reservoirs in the surroundings of Serra da Capivara National Park, area of environmental preservation in the caatinga in the State of Piauí, with semi-arid climate, were evaluated in order to select the consortia of fungi capable to degrade and detoxify these dyes. The mixed fungal culture from Caldeirão Escuridão (CE) reservoir was the most efficient in the degradation and detoxification of the dyes tested.