Background: Steatohepatitis is a morphological pattern of liver injury that, in non-alcoholic patients, may represent a form of chronic liver disease currently known as non-alcoholic steatohepatitis (NASH). Probiotics, Lactobacillus sp. and Bifidobacterium sp., have been proposed to prevent and treat different inflammatory conditions of the gastrointestinal tract. Objective: To examine the effect of Lactobacillus plantarum (L. plantarum) on the liver damage of non-alcoholic steatohepatitis (NASH) rats. Materials and Methods: Male Sprague-Dawley rats were randomly divided into three groups. Group 1 (control, n = 8) was fed with phosphate-buffered saline (PBS) 1 mL/rat. Group 2 (NASH, n = 8) was fed with 100% fat diet for 6 weeks. Group 3 (NASH + L. plantarum, n = 8) was fed with 100% fat diet plus L. plantarum 1.8 × 109 colony-forming unit/mL was suspended in PBS by gavage twice a day at an interval of 4 h for 6 weeks. All rats were sacrificed to collect blood and liver samples at the end of the treatment period. Results: The levels of hepatic malondialdehyde (MDA) and tumor necrosis factor alpha (TNF-α) were increased while the expression of peroxisome proliferator activated receptors gamma (PPAR-γ) was decreased significantly in the NASH group as compared with the control group. Histopathology from the NASH group showed macrovesicular steatosis, hepatocyte ballooning, and lobular inflammation. The NASH + L. plantarum group had attenuated the levels of MDA and TNF-α, enhanced PPAR-γ expression, and improved the histopathology. Conclusion: L. plantarum treatment can attenuate oxidative stress, inflammation, and improvement of histopathology in rats with NASH.