This study evaluated the Nephrotoxic effect of water soluble fraction (WSF) of Bonny Light Crude Oil (BLCO). After preparation of the WSF and a range finding test, the Wistar albino rats were administered three concentrations (25%, 50% and 100%) of WSF of BLCO for 30 and 60days. Data from the study showed that Urea concentration increased significantly (p≤0.05) with increasing dose of BLCO ranging from 14.71 mg/dl in the control to 35.28 mg/dl in the 100% group after 30days and 14.28 mg/dl in

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... e control to 41.08mg/dl in the 100% group after 60days, Creatinine concentration increased significantly (p≤0.05) from 0.22 mg/dl in the control to 0.82mg/dl in the 100% group after 60 days administration while electrolyte (Na, K, Cl) concentration increased significantly (p≤0.05) with increasing dose of BLCO after 60days administration. Histopathological examination of the kidney was characterized by partial partitioning of the glomerular tufts, obliteration of the Bowman's capsule and distortion of the renal tubules. The findings in this research suggest that WSF of BLCO induced nephrotoxicity.