The study had two objectives. The first was to determine the use of the physical habitat by the 25 most common native freshwater fishes of Oregon, and the second was to evaluate the use of a large computer database of museum records in the determination. The database encompasses 2021 collections made by various field workers from 1880 to 1984. Statistically distinct habitat use patterns appear for 17 of the species for temperature, 17 for substrate, 19 for stream width, and 22 for current velocity. Habitat use identified from this statistical evaluation is generally consistent with the subjective evaluations of field ichthyologists. A large computer database compiled from field notes of many collectors allowed useful generalizations concerning species habitats.