Samples of benthic oligochaetes were collected from March 1993 to February 1994 in channels of the Paraná river. 14 species were identified for which the average density was determined at five sites representing different environmental conditions. Principal component analysis showed strong correlation in occurrence with granulometric texture and organic matter in the sediment of the dominant species Narapa bonettoi as well as of Haplotaxis aedeochaeta, Limnodrilus hoffmeisteri and Pristina americana. The results are discussed in relation to sampling site factors like sediment structure and seasonal changes in water level.