We tested the hypothesis that Moringa oleifera impairs the morphology and functions of the kidney in rats. Twenty-four adult male Wistar rats were employed in the study. Rats of Control Group I received physiological saline while rats of Groups II - IV received 250, 500 and 750 mg/kg bodyweight of methanolic extract of Moringa oleifera respectively for twenty one days. No behavioral anomalies were observed in rats of Groups I - IV. Rats of Control Group I gained statistically significant increased bodyweight while rats of Groups II - IV experienced non-significant decreased bodyweight during experimental procedure. (P <= 0.05). No statistical significant differences (P <= 0.05) were observed in the analyses of the relative weights of kidneys of rats of Groups I - IV. Histological examinations showed normal cyto-architecture of the kidneys of rats of Group I while the Capsular spaces of the kidneys of rats of Groups II - IV appeared wider than those of Group I. Statistical analyses showed significant higher levels (P <= 0.05) of Alanine and Aspartate Transaminases, and serum urea in rats of Groups II - IV in a non- dose-dependent manner when compared to rats of Group I. Our findings are consistent with the stated hypothesis.