OBJECTIVE To investigate the potential toxic or adverse effect of transgenic human alpha-lactalbumin powered milk on rats. METHODS Weanling Wistar rats were randomly divided into seven groups according the weight: three transgenic milk powder (T) groups, three non-transgenic milk powder (N) groups and the control (C) group. The diets of T groups contain 15%, 30% and 60% transgenic human alpha-lactalbumin milk powder. The diets of N groups contain 15%, 30% and 60% non-transgenic human alpha-lactalbumin milk powder for 90 days. The diet of C group contains only basic feed. Haematological and biochemical parameters was measured during the study (at 45th and 90th of the experiment). At the end of the 90th day, organ tissues analysis was performed. RESULTS There were no transgenic human alpha-lactalbumin related adverse effects on the body weight, food intake, food consumption, hematology,serum biochemistry, as well as histopathology. CONCLUSION There were no signs of toxic and adverse effects for transgenic human alpha-lactalbumin powdered milk on rats.