Background: Abundant experimental evidence indicates overproduction of angiotensin Ⅱ in the injured liver, and a role in stimulation of hepatic stellate cell (HSC) activation and fibrogenesis thereby, representing an attractive antifibrotic target. The aim of this study was to examine the antifibrotic effect of losartan on histopathologic level in chronic HCV patients. Methods: A prospective study on fifty patients with chronic HCV and liver fibrosis proved by liver biopsy was conducted. They included patients who did not respond (n=36) or comply (n=2) or receive therapy due to established cirrhosis (n=10), or refused to receive (n=2) combined interferon and ribavirin therapy. They were divided randomly into 2 groups. The 1st group (n=25) was given losartan 50 mg OD for 1 year and the 2nd group (25 patients) was given silymarin, 140 mg t.i.d., (silymarin group). Liver biopsy was done at baseline and 1 year from the onset of treatment (end of study). Results: In the second liver biopsy after 1 year, the decrease in fibrosis stage was significantly different between losartan group and silymarin group (a decrease of 1.88±0.96 (50.9％) vs. 0.45±0.93 (11.7％), respectively; P<0.01). In patients treated with losartan, regression in fibrosis stage was observed in 14/16 patients vs. 2/11 in silymarin group (P<0.01). No differences were observed in inflammation grades in both groups. A significant increase in albumin and prothrombin levels and a decrease in systolic blood pressure were found in losartan but not in silymarin group (P=0.009, 0.001 & 0.018 respectively and P=0.158, 0.603 & 0.288, respectively). Conclusions: Histopathological scores showed that losartan had an inhibitory effect on progression and even led to regression of fibrosis stage but had no effect on the grade of inflammation.