Abstract: The use of L-arginine (ARG) is common in supplements, whereas, Monosodium Glutamate (MSG) is widely used as flavor enhancing food additive. Thus, ARG and MSG may be present together in human diets, warranting this study aimed at investigating the effect of concomitant ingestion of ARG and MSG on some biochemical indices in male rats. Twelve male albino rats were grouped into three (n = 4) and concomitantly exposed to 0:0, 20:5 and 60:15 mg kg-1 of ARG:MSG. Exposure was peroral and every twenty four h for 28 days. ARG plus MSG treatment caused a significant (p≤0.05) increase in Feed Efficiency (FE) (Low dose: 5.23±22%; High dose: 5.60±11%), whereas, it decreased (p≤0.05) the serum Total Cholesterol (T-Chol) (low dose: 80.83±0.11 mg/100 mL, high dose: 92.55±0.14 mg/100 mL), triacylglycerol (TAG) (low dose: 179.91±0.09 mg/100 mL, high dose: 119.77±0.32 mg/100 mL) and malondialdehyde (MDA) (low dose: 5.00±0.07 mg/100 mL, high dose: 24.36±0.10 mg/100 mL) concentrations of the rats in a dose dependent manner. However, (at the high dose) the increase in Body Weight (BW) (0.08±0.07 kg), Feed Intake (FI) (0.40±0.03 kg) and Water Intake (WI) (0.65±0.18 L) induced by ARG plus MSG exposure was not significant (p≥0.05), suggesting non treatment related effect on these routine parameters. However, exposure to ARG plus MSG may significantly improve feed efficiency, lipid metabolism and antioxidant capacity in the male rats.