Background and objectives: This study compares the effect of aspartame consumption alone and combined with vitamin C and E over biochemical parameters related to liver and kidney function and oxidative stress biomarkers. Methodology: 5 groups of rats - Control I: treated with drinking water. Control II: 0.2 ml of olive oil (vehicle for vitamin E). Experimental Groups - Group I: aspartame (40 mg/Kg). Group II: aspartame (40 mg/Kg) plus vitamin C (150 mg/Kg). Group III: aspartame (40 mg/Kg) plus vitamin E (100 mg/Kg). All the treatments were administered by gavage once a day during 60 days. Results: Aspartame combined with vitamin C or E led to a decrease on body weight of 7% and 10%, respectively. Total cholesterol concentration was decreased when aspartame was combined with vitamin C (7%) or E (20%). AST activity was increased by aspartame which was prevented when its consumption was combined with vitamins C or E. ALT activity was decreased in presence of vitamin C (40%) or E (36%). Aspartame with vitamin C or E decreases level of creatinine 31% and 30%, respectively. Vitamin E decreased catalase activity (31%). Inclusion of vital C and E reduced the concentration of oxidative stress biomarkers, brain 8-OHdG and urinary isoprostane, when compared with the group just receiving aspartame. Conclusion: The results obtained in the present study suggest that combining vitamin C or E with the administration of aspartame has a protective effect over liver and kidney functions as well as protective effect agains oxidative stress.