The efficacy of a regional stream classification system, based on the principle that streams reflect the character of the lands they drain, was evaluated in Arkansas. The classification consisted of six aquatic ecoregions defined by relatively homogeneous types of land-surface form, soil, potential natural vegetation and land use. Fish, physical habitat and water quality were sampled in 22 streams throughout the state. Data subjected to ordination analysis generally showed greater similarity in streams within the same ecoregion than in streams in different ecoregions. The patterns developed separately from fish, physical habitat and water quality data sets were relatively concordant. The null hypothesis that the classification did not reflect fundamental differences among the streams was rejected. We concluded that a regional stream classification is potentially useful for evaluating and managing streams. The identification of regions containing streams with similar character can aid in selecting reference streams for impact assessments or in selecting monitoring sites from which results may be extrapolated regionally.