Abstract: OBJECTIVE: To explore the toxicity of sodium hyaluronate on SD rats in sensitive period of teratogenesis. METHODS：Pregnant rats were divided randomly into five groups，three sodium hyaluronate groups (1 333， 667 and 333 mg/kg)，one negative control given deionized water，and one positive control given Aspirin (250 mg/kg). There were at least 12 pregnant rats in each group. During the sensitive period of teratogenesis (the 7th to 16th day of gestation)，the pregnant rats of each group were given test sample orally once a day for ten days. On the 20th day of gestation，the pregnant rats were sacrificed. Embryonic and fetal development were evaluated，appearance，viscesal and skeletal abnormalities were observed. RESULTS：In sodium hyaluronate groups，the weight of pregnant rats and uterus including fetuses，living fetus rate，dead fetus rate，body weight，length of body and tail of fetuses were not significantly different from negative control. No abnormality of skeleton，organ and body was identified in fetuses of groups treated with sodium hyaluronate. CONCLUSION：At dosages used in this study，sodium hyaluronate had neither maternal toxicity nor teratogenecity in pregnant SD rats.

Key words: sodium hyaluronate, SD rats, teratogenecity