Introduction. Liver fibrosis is caused by continuous wound healing responses to various harmful stimuli, including viral infection, drugs, alcohol, and autoimmune liver disease. The purpose of this study was to examine the effects of extracts of Periplaneta americana (EPA) in rats with pig serum-induced liver fibrosis to preliminarily assess the antifibrotic effect of EPA. Material and methods. Seventy rats were randomly divided into 7 groups (10 rats in each group): HC, the healthy control group; FC, the fibrotic control group; TL, low-dose EPA treatment group group; TM, medium-dose EPA group; TH, high-dose EPA treatment group; TC1, Panax notoginseng/Salvia mitiorrhiza treatment control group 1; TC2, colchicine treatment control group 2. TC1 and TC2 were used as the positive control to demonstrate the difference between EPA and the effects of other compounds. The liver fibrosis model was induced by intraperitoneal injection of 0.5 mL pig serum twice a week for 13 weeks in all groups except for the HC group. The hepatic fibrosis model was established at the 7th week, and followingly, the corresponding compounds were administered once a day in all groups for 6 weeks. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity was determined in rat blood serum. We also measured liver fibrosis-related serum markers, including hyaluronic acid (HA), laminin (LN), type III pre-collagen (PC-III) and type IV collagen (IV-C). Hematoxylin and eosin (H&E) and Masson stainings were used to assess liver morphology and determine the stage of fibrosis. Immunohistochemistry was used to detect the protein expression of NF-kappa B, alpha-smooth muscle actin (alpha-SMA), transforming growth factor-beta 1 (TGF-beta 1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in rat liver tissue. Results. Compared with that of the HC group, the liver tissue of the FC group presented obvious liver damage and collagen deposition. The serum levels of ALT, AST, HA, LN, PC-III and IV-C and the expression of NF-kappa B, alpha-SMA, TGF-beta 1 and TIMP-1 in the FC group were significantly higher than those in the HC group, the EPA treatment groups, the TC1 group and the TC2 group (P < 0.01). The levels of serum ALT, AST, HA, LN, PC-III and IV-C and the expression of alpha-SMA, NF-kappa B, TGF-beta 1 and TIMP-1 in the TL, TC1 and TC2 groups were significantly higher than those TM and TH groups (P < 0.05). EPA treatment significantly improved liver function, decreased collagen deposition and reversed the pathological changes related to liver fibrosis. Conclusions. We found that EPA could reduce liver inflammation, suppress liver cell degeneration and necrosis, and reduce the formation of liver fibrous tissue. Its mechanism might be associated with inhibiting the expression of TGF-beta 1, TIMP-1, NF-kappa B and alpha-SMA to block signal transduction pathways in the hepatic fibrosis process. Therefore, EPA, as a traditional Chinese medicine, might be potentially used to prevent and treat hepatic fibrosis in the future. However, further more experiments are necessary to verify its effectiveness and possible signaling pathways.