Background: 5-Fluorouracil (5-FU) is one of the extensively used chemotherapeutic agents for different human malignancies. It has severe side effects and is considered a nephrotoxic agent. Captopril is one of the angiotensin-converting enzyme inhibitors (ACEI) used in treatment of hypertension and congestive heart failure. It is also an effective radical scavenger and antioxidant due to its free thiol group. Grape seeds extract is one of the effective radical scavengers with antioxidant, anti-proliferative and anti-inflammatory properties.Objective: The present study was designed to assess the probable protective role of captopril and grape seeds extract against 5-FU-induced nephrotoxicity in adult male albino rats. WESAM ABD EL-SALAM ABD EL-WAHAB et al., 586Materials and Methods: Forty eight adult male albino rats were divided into 8 equal groups; Group I kept as the control group, Group II (grape seeds consumed group), received aqueous grape seeds extract (500 mg/kg/day) orally by gastric tube. Group III (captopril group), injected intraperitoneally by captopril solution (60 mg/kg) once daily. Group IV (grape seeds & captopril), Group V (5-Fluorouracil group), injected intraperitoneally by 5-FU solution (20 mg/kg) once daily. Group VI (grape seeds/5-FU), Group VII (captopril/5-FU) and Group VIII (grape seeds & captopril/5-FU). Treatment was continued at the same time daily for 4 weeks. At the end of the experiment, final body weight, blood urea nitrogen (BUN), creatinine (Cr) and uric acid levels were measured. Also, specimens of right kidneys were taken for histological and immunohistochemical studies with anti-inducible nitric oxide synthase (iNOS).Results: 5-FU resulted in a significant reduction in final body weight and a significant elevation of (BUN), (Cr) and uric acid levels. Moreover, glomerular and tubular distortion, vacuolated epithelial lining, intraluminal acidophilic hyaline casts, congested peritubular capillaries, interstitial inflammatory infiltration, and increased fibrosis within the renal interstitium. The immunohistochemical expression of iNOS supported kidney impairment in the 5-FU group. Treatment with either grape seeds or captopril revealed some improvement in the final body weight, biochemical markers and histological changes. The best effect was encountered when grape seeds and captopril were combined. Conclusion:and Recommendation: Grape seeds and captopril succeeded in ameliorating 5-FU induced nephrotoxicity with a better effect by their combination. So, it is recommended to use grape seeds extract and captopril during chemotherapy with 5 fluorouracil to reduce its renal toxicity.