Before treatment with a 3 mg/l Noxfish (0.15 mg/l active ingredient; rotenone) for 4 8 hours. benthic invertebrate communities were quantitatively sampled with a modified Surber net. Then spring, summer. and fall post-rotenone samples were taken monthly a t each of four Strawberry River stations for five years. Statistical analyses of the data indicated that the application of rotenone had a significant effect on the following species density: Cinygrnula sp., Pteronarcella badia , Hesperoperla pucflca, Hydropsyche sp.. and Brachycentrus americanus. Thirty-three percent of the benthic invertebrate taxa a t the four stations showed resistance to rotenone. Up to 100% of Ephemeroptera, Plecoptera and Trichoptera species were missing after the second rotenone application. Forty-six percent of the taxa recovered within one year, but 2 1% of the taxa were still missing after five years. Of the 19 taxa still missing, 47% were Trichoptera. 21% were Ephemeroptera. 16% were Plecoptera, 11% were Coleoptera, and 5% were Megaloptera.