In the Reduction of Endpoints in NIDDM (noninsulin–dependent diabetes mellitus) with the Angiotensin II Antagonist Losartan study (RENAAL study), Losartan reduced the risk of the doubling of serum creatinine concentration by 25% and of end stage renal disease (ESRD) by 28%. Methods: 40 albino rats were enrolled in this study, and they were divided into four main groups, each group 10 rats. Where, group I, serves as a control, and group II was treated with Gentamicin 80mg/kg. The group III was treated with Losartan. While, group IV was treated with Losartan and Gentamicin. Results: showed that Losartan has statistically significant nephro-protective effects. Their nephro-protective effects were assessed by:-1- histopathological studies. 2- Measuring serum levels of BUN, and, creatinnine. Conclusions: Losartan has renal-protective effects.