The diversity of Chironomidae larvae was studied in two water courses in Catamarca, the Río River and El Simbolar Stream. They are both located in ecoregions, the former in the Puna and the latter in the Chaco Serrano. The aim of this paper was to analyze the diversity of Chironomidae in relation to environmental variables in watercourses in Catamarca. Sampling was performed in periods of high and low water, using a Surber sampler (300 μ and 0.09 m-2).