Mono sodium glutamate (MSG) is commonly marketed as a flavor enhancer and is used as a food additive. The present study was carried out to study the effect of MSG at two oral low doses of 0.6 and 1.6 mg/g body weight on liver functions during feeding period (2 weeks) in albino rats and to investigate the effect of oral administration of N-acetylcysteine on hepatotoxicity induced to rats by (MSG). six groups as follows; group 1: control; group 2: received oral 0.6 mg/g body weight of MSG, group 3: received oral 1.6 mg/g b. wt of MSG, group 4: received oral Nacetylcysteine in a dose of 200 mg/kg b. wt. group 5: received oral 0.6 mg/g b. wt of MSG plus 200 mg/g body weight N-acetylcysteine and group 6: received oral gavage of 1.6 mg/g b. wt of MSG plus 200 mg/g b.wt N-acetylcysteine on a daily basis. The rats were sacrificed on the fifteenth day of the experiment. Measuring serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP); albumin, total protein, total bilirubin, lactate dehydrogenase (LDH) enzyme and glutathione reductase (GR) was done. Histopathological examination of liver was performed. Many biochemical changes of statistically significance change were obvious. Inflammatory cells infiltrated, apoptotic bodies, necro-inflammatory foci were observed. The results suggested that N-acetylcysteine had potent hepatoprotective and antioxidant effects in MSG - hepatotoxic rats.