The aim of this study was to investigate subchronic toxicity of Flos Puerariae.Methods According to procedures and methods for toxicological assessment of food (2003 edition), eighty SD mice were randomly divide into four groups (10 male and 10 female in each group). 0,6.25,2.5,5.0 g/kg.BW of Flos Puerariae extract were given by gavage for 90 days respectively. On the 45th day, samples of blood were collected from tails to perform complete blood count and biochemical tests. After 90 days, samples of blood were collected and were used for blood count and biochemical tests; livers, kidneys, spleens and testicles(ovaries) were weighed; pathological examinations of livers, kidneys, spleens stomach intestines testicles and ovaries were conducted. Results The results showed that indexes including weight, food intakes, food utilizations, and organ-body ratios in treatment groups are not significant different from those in the control group (P>0.05); in the interim and at the end of experiments, the blood count and biochemical tests of some certain treatment groups have statistical difference (P<0.05); however, the difference is in a normal range and has no biological significance; minor pathological changes have been discovered in a few treatment groups through the histopathology examination.Conclusion Flos Puerariae extracts have no adverse effect on the growth performance of mice under the doses of pueraria flower in a range of 6.25-25.00 g/kg BW. Moreover, Flos Puerariae extracts haven't caused obvious toxic and side effects on experimental animals.