Reactive oxygen species (ROS) are key mediators of mammalian cellular damage and are associated with diseases such as aging, arteriosclerosis, inflammation, rheumatoid arthritis and diabetes. Type 1 diabetes develops upon the destruction of pancreatic β-cells, which is partly due to ROS activity. In this study, we investigated the cytoprotective and anti-oxidative effects of fractionated mulberry extracts in mouse insulin-producing pancreatic β-cells (MIN6N cells). Treatment with hydrogen peroxide (H2O2) induced significant cell death and increased intracellular ROS levels, lipid peroxidation and DNA fragmentation in the MIN6N cells. Fractionated mulberry extracts significantly reduced the H2O2-dependent production of intracellular ROS, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and lipid peroxidation. In addition, mulberry extracts inhibited DNA fragmentation induced by H2O2. Thus, the antioxidant properties of mulberry extracts in pancreatic β-cells may be exploited for the prevention or treatment of type 1 diabetes.