Objective: Liver fibrosis is a common pathological condition that can lead to liver failure. Previous studies demonstrated that 5-fluorouracil (5-FU) is an effective agent in preventing fibrosis. This experimental study aimed to evaluate the efficacy of 5-FU therapy on liver fibrosis in rats. Material and Methods: Thirty-eight rats were divided into 3 groups: Group 1 (sham-operated, n=10), the bile duct (BD) was exposed but not ligated; Group 2 [bile duct ligation (BDL)-saline, n=14], the BD was ligated and normal saline solution was given; Group 3 (BDL-5-FU, n=14), the BD was ligated and treated with 5-FU. The liver and blood samples were harvested at postoperative day 21. Liver function analyses, tissue hydroxyproline (HP) content, and serum and tissue transforming growth factor beta 1 (TGF-β1) levels were determined. The liver sections were analyzed and percentage of tissue collagen content was measured. Results: There were no significant differences between the groups in terms of tissue (p=0.748) and serum (p=0.123) levels of TGF-β1. Mean HP level in the sham-operated, BDL-saline, and BDL-5-FU groups were 253±42 ng/L, 360±32 ng/L and 305±41 ng/L, respectively. 5-FU significantly decreased HP level (p=0.036). Mean percentage of collagen content in the sham-operated, BDL-saline, and BDL-5-FU groups were 0.99±0.39%, 4.92±1.03%, and 2.62±0.64%, respectively. 5-FU significantly reduced collagen accumulation (p<0.001). Conclusion: 5-FU has a preventive effect on liver fibrosis in rats. This result suggests that 5-FU can be a potential agent for prevention of liver fibrosis in clinical practice.