The imbalanced expression of matrix metalloproteinases (MMPs) is associated with liver fibrosis, one of the most common chronic liver diseases. Enhanced expression of MMPs by gene therapy is emerging as a promising antifibrotic strategy, but the effectiveness of this approach depends on reliable systems for delivering MMP genes. Here, we evaluated a newly designed hyaluronic acid (HA)-shielded delivery system for systemic administration of plasmid DNA encoding MMP13 (pMMP13), and tested whether the enhanced expression of MMP13 ameliorates liver fibrosis in mice. In the CCl(4)-induced liver fibrosis model, systemic administration of pMMP13 using HA and polyethylenimine (PEI) significantly increased the expression of MMP13 and reduced collagen deposition. Moreover, following delivery of pMMP13 in a HA-shielded PEI complex, the serum levels of aspartate transaminase were reduced to levels approaching those in untreated normal mice. These results indicate that the delivery of pMMP13 using HA-shielded PEI enhances the efficiency of MMP13 expression in the liver, and highlight the potential of pMMP13 gene therapy as an antifibrotic strategy.