OBJECTIVE To observe the toxic effects of single administration and repeated administration of Qingzi granules for 13 weeks on rats, and to evaluate their preclinical safety. METHODS For the single dose toxicity experiment, SD rats were randomly divided into two groups, vehicle control group(deionized water) and Qingzi group(18 g·kg-1), which were given in a volume of 30 mL·kg-1 per time, twice in 24 h(interval more than 4 h), and observation was performed for 14 d after administration. The toxicity reaction was evaluated through observation of body weight change and pathological anatomy. For the repeated dose toxicity experiment, juvenile SD rats(postnatal day, PND 4) were randomly divided into vehicle control group (deionized water) and low, medium and high dose of Qingzi groups(1, 2 and 4 g·kg-1). The rats were orally administered twice daily with vehicle or Qingzi for 13 weeks in a volume of 10 mL·kg-1 per time. A recovery period of 4 weeks was followed. Test items included clinical observations, body weight measurement, food intake measurement, hematology test, biochemical test, urinalysis, sex hormone level determination, cellular immune function assay, growth indexes and histopathology test. RESULTS For the single dose toxicity experiment, Qingzi granules were orally administered to SD rats without significant toxicity, and the maximum-tolerated dose was greater than 18 g·kg-1. In the repeated dose toxicity test, juvenile SD rats were given Qingzi granules by gavage and repeated administration for 13 weeks, the no observed adverse effect level was 2 g·kg-1. The target organ of toxicity was the liver and the main toxic effect was inflammatory necrosis of hepatocytes, no dose-dependent relationship. CONCLUSION No overt toxicity of Qingzi granules was observed on the tested animals within the intended clinical dosage range.