How macroinvertebrate respond to human disturbances can be characterized following two major approaches. The traditional taxonomic approach has been extensively used. Since the nineties, another approach based on functional traits has been experiment and offer a better understanding of community-environment relationships and functioning of ecosystems facing human impacts. In this study, we assessed sediment quality in a large river in North America by exploring the relationships between chemical contamination and benthic community structure using the functional trait approach. This study was carried out in the St-Lawrence River, an essential waterway exposed to many anthropogenic stresses such as industrial and municipal wastewater or agricultural activities. Macroinvertebrates were collected in 59 sites. Organic and inorganic contaminants as well as sediments characteristics (grain size, organic matter, nutrient, etc) were measured in sediment. Seventeen biological or ecological traits of taxa were coded, taking into account regional climate and ecosystem specificities. The goals of this study were to: (1) link macroinvertebrate trait combinations to environmental conditions and (2) link trait combinations to quality guidelines developed for the assessment of sediment quality in Quebec.