In this work the composition and the spatial distribution of a community of aquaticinsects were studied in order to asses the ecological quailty of ViIIeta River Iocated inthe Deparment of Cundinamarca. The hidrologic characteristics of this lotic systermwere also investigated in order search for biotic and abiotic interactions. From February:1999 to January 2000, samples from two Iocalities were taken monthly and subjected tophysicochemical and biological analysis. The most important famlies wereChironomidae (Diptera), Baetidae (Ephemeroptera) and Hydropsychidae (Trichoptera)Both the physicochemical and biological characteristics of this ecosystem are rainfallpattern dependent.