Benthic organisms are generally considered to be good indicators of environmental conditions of aquatic ecosystem. The present study was undertaken to study the pre-impoundment composition, abundance, distribution and diversity of the macroinvertebrate fauna of Elemi River, Ado-Ekiti, while using these organisms as water-quality bioindicators. Physicochemical, metals and benthic samples were collected biweekly at four stations between April –July, 2015, using standard methods of APHA (1998). The mean values of triplicate samples of physicochemical parameters include pH (6.82±0.06), temperature (27.05°C ± 4.35), TDS (0.07 ± 0.0001), DO (11.15 ± 1.88), BOD (5.8 ± 0.71), NO3 (57.08 ± 6.48), SO4 (76.14 ± 10.4). For the metals, the mean values are Pb (0.01 ± 0.0001), Cr (0.21 ± 0.04), Cu (0.07 ± 0.003), Mg (152.68 ± 79.5), Zn (2.05 ± 5.19), and Fe (1.98 ± 0.21). When compared with the WHO permissible standards for freshwaters, DO, BOD and NO3 had mean values that were significantly higher than the WHO standards for drinking and agricultural purposes. Also, metals including Cr, Mg, Zn, and Fe had mean values significantly higher than the WHO standards. Seven families of macroinvertebrates representing five orders of Mollusca (66.6%), Coleoptera (14.6%), Plecoptera (12.7%), Hemiptera (4.3%), and Tricoptera (1.8%) were recorded during the period of study. Of the total collected macroinvertebrates, insects comprised only 33.4%, but they are more diverse compared with the gastropods which made up the highest (66.6%) percentage, but are less diverse. Their high abundance coupled with high concentrations of some physicochemical parameters indicates high impact of anthropogenic activities and may result into high organic pollution of the river. Elemi River thus experiences degradation as it flows downstream and benthic macroinvertebrates can serve as a good biological indicator to monitor the river health.