Objective:To investigate the protective effect of mycophenolate mofetil(MMF) on insulitis and pancreatic β-cell apoptosis in NOD mice. Methods:Twenty-two female NOD mice of eight-week age were randomly divided into the following two groups:the control group and the MMF-treated group. MMF(30 mg/kg) was administered daily by intragastric intubations throughout the experimental period(30 days) and the control group received an equivalent amount of 0.9% NaCl intragastrically. Before and during all experiments, blood glucose of all mice were assessed. Following treatment, five mice of each group were anaesthetized and then were killed to remove pancreas immediately. The rest mice were sacrificed when they got diabetes or twenty-week age. The degree of insulitis and the morphological changes of pancreatic β-cells apoptosis were determined by light microscope and TUNEL assay. Results:The concentration of blood glucose in MMF-treated group were as same as those in the control group before and during the experiment(P > 0.05). The insulitis scores and severity of insulitis and the percentage of β-cell apoptosis in the MMF-treated mice were significantly lower than those of the control group(P < 0.01). Conclusion:MMF treatment could ameliorate early pancreatic injury via the inhibition of insulitis and β-cell apoptosis in NOD mice. It suggests that MMF could be effective in delaying and preventing diabetes especially if treatment is started before the onset of diabetes.