Objective To observe the chronic toxic effect of the genetically modified rice which harboring human lactoferrin (hLF) gene on rats. Methods Based on gender and weight, 180 weanling SD rats were randomly divided into three groups: transgenic rice group, parental rice group and AIN-93 normal control group. They were fed for 12 months. Body weight, food consumption, hematology and clinical biochemistry were observed during the experiment period. The rats were sacrificed at the end point for organ weight measurement and pathological examination. Results The differences of some indices of hematology (LYM%, GRN%) and clinical biochemistry (ALT, AST, GLU) between hLF rice group, parental rice group and AIN-93 group were significant (P<0.05) while no other significant difference was observed. Conclusion There was inadequate evidence to indicate the hLF rice had adverse effects on rats.