In current study, we investigated the protective effects of the anthocyanin fraction (AF) obtained from the purple-fleshed sweet potato on hepatic fibrosis induced by dimethylnitrosamine (DMN) administration in rats. Treatment with DMN for 4 weeks produced marked liver fibrosis as assessed by increased serum alanine aminotransferase and aspartate aminotransferase activity and hepatic collagen content. These increases were inhibited by treatment with AF prior to the administration of DMN. In addition, AF inhibited DMN-induced reductions in rat body and liver weights in a dose-dependent manner. Histopathological evaluation of the rat livers revealed that AF reduced the incidence of hepatic fibrosis lesions and inhibited DMN-induced increases in α-smooth muscle actin (α-SMA) and collagen type I and III expression levels. AF also decreased DMN-induced expression levels platelet-derived growth factor receptors-beta, tumor necrosis factor-alpha and transforming growth factor-beta. This study demonstrates that AF administration can effectively improve liver fibrosis caused by DMN, and may be used as a therapeutic option and preventive measure against hepatic fibrosis.