We modified the Index of Biotic Integrity (IBI) to characterize the fish assemblages and evaluate the biotic integrity of four forested streams in the Lower Ouachita Mountains Ecoregion, Arkansas. We related differences in IBI scores with corresponding differences in chemical and physical characteristics of the streams, including the varying intensities of forest management. Analysis of variance and comparison of mean IBI scores among the four streams revealed significant differences between reference and even-aged treatments and between even-aged and uneven-aged treatments (P < 0.05). Turbidity and total suspended solids were inversely related to IBI scores. Further refinement of the IBI should enable its use in the Ouachita Mountains Ecoregion to help assess site impacts, monitor trends in stream biotic integrity, and assess effectiveness of forest best management practices.