Macroinvertebrate communities and environmental variables were assessed in an Ankara Stream receiving high organic and industrial wastes. Environmental data were used to explain biological variation using multivariate techniques provided by the program CANOCO. The ordination method CCA (Canonical Correspondence Analysis) was applied to evaluate the relationships between environmental variables and distribution of macroinvertebrate genera. Data sets were classified by TWINSPAN (Two Way Indicator Species Analysis). In this investigation, macroinvertebrate communities have been shown by CCA ordination to be related to TOM (total organic matter), ammonia, cadmium, pH, lead, dissolved oxygen, conductivity (EC), phosphate, boron, nitrite and hardness, with TOM, ammonia, cadmium and pH emerging as the most significant environmental variables. Epeorus was a TWINSPAN indicator for the slightly polluted upstream site 1. Physa was a TWINSPAN indicator for the polluted downstream sites.