sixty-seven streams located south-west of lake nipigon, ontario, were sampled for brook trout and macroinvertebrate orders. sixteen orders were used to determine if their community structure significantly changed in different brook trout habitat and different brook trout densities (no brook trout, one to fifteen brook trout or more than fifteen brook trout). though the orders odonata, oligochaeta, trichoptera, chironomidae, nematoda, simuliidae, gastropoda and plecypoda varied in response to brook trout habitat quality and abundance, the community structures did not change significantly. pollutant sensitive orders, trichoptera, ephemeroptera, and plecoptera that are used as indicators and share similar habitat to brook trout did not significantly change in response to brook trout densities. future direction may involve identifying macroinvertebrates to family or genus level to detect community changes, or analyzing further data such as invertebrate biomass, diversity or richness in these streams.