To investigate the effects of fermented brown rice (FBRA) on the development of hereditary hepatitis in Long-Evans Cinnamon (LEC) rats, we compared the incidence and grades of acute hepatitis among rats fed 5% and 10% FBRA in the conventional diet and the conventional diet alone. Both the 5% and 10% FBRA-supplemented diets indicated a tendency to prevent the development of hepatitis, and the significant effect of 10% FBRA was observed until 16-17 weeks of age in the accumulated incidence and survival ratio compared with the unsupplemented conventional diet, although no significant difference was observed between 5% and 10% FBRA-supplemented diets. At the age of 12 weeks, which is just before the rats develop hepatitis, serum copper levels in rats fed either of the test diets were similar to those in rats fed the conventional diet. Furthermore, the copper concentration in liver tissue at 12 weeks of age was not changed by the test diet. These results suggest that FBRA has preventive effects on the development of hepatitis in LEC rats and may play an important role in protecting the liver against the free radicals induced by copper accumulation in the liver.