The benthic invertebrates of Trout Creek in northwest Colorado were sampled from natural and multiplate artificial substrates at four stations over three seasons. Although artificial substrates collected lower numbers/m2and number of species, the greatest difference between substrates was exhibited in their respective insect communities. Artificial substrates collected fewer caddisflies and beetles and more dipterans, mayflies and stoneflies than were present in the natural substrates. Functional groups also exhibited this difference with scrapers predominant on natural substrates but not important on the artificial substrates. The multiplate substrates appeared to favor shredders at the upstream sites and filterers and gatherers at the rest of the stations. This probably is related to accumulation of debris on the samplers. These differences need to be considered when interpreting data from artificial substrates in mountain streams.