Solanum nigrum (Solanaceae) has been used in traditional folk medicine for its hepatoprotective agent. The purpose of this study was to investigate the effects of Solanum nigrum extract (SNE) on thioacetamide (TAA)-induced liver fibrosis in mice. SNE reduced the hepatic hydroxyproline and alpha-smooth muscle actin protein levels of TAA-treated mice. SNE inhibited TAA-induced collagene (alpha1)(I) and transforming growth factor-beta1 (TGF-beta1) mRNA levels in the liver. Histological examination also confirmed that SNE reduced the degree of fibrosis caused by TAA treatment.Oral administration of SNE significantly reduces TAA-induced hepatic fibrosis in mice, probably through the reduction of TGF-beta1 secretion.