OBJECTIVE: The previous experiments of our department had demonstrated that Baicalin (BC) and Tetramethylphyrazine (TMPZ) had protective effect against infectious brain edema in rats and rabbits. In the present study we would look for whether BC and TMPZ could influence HSP70 expression with heat shock responres(HSR). METHODS: Twentyseven male rats were randomly divided into: ①NS group (n=3); ②HSR+pertusis bacillil (PB) group (n=3); ③PB group (n=3); ④BC group, in which the rats were subdivided into three groups (n=3 in each group) with BC injected intraperitoneal at 48 mg/kg, 120 mg/kg, 194 mg/kg respectively. ⑤TMPZ group, 9 rats were evaluated as follows, with 37.5 mg/kg, 100 mg/kg, 160 mg/kg TMPZ injected intraperitoneal respectively. The animals were killed after 28 hours and the expression of HSP 70 was evaluated by western blot analysis. RESULTS: HSP70 in the brain tissues was significantly elevated in the HS+PB group and 120 mg/kg BC, 194 mg/kg BC, 100 mg/kg TMPZ, 160 mg/kg TMPZ groups. HSP70 was only at base levels in the PB and NS groups and 48 mg/kg BC, 37.5 mg/kg TMPZ groups. CONCLUSIONS: BC and TMPZ could influence HSP70 expression with HSR. The protective mechanism of BC and TMPZ on infectious brain edema in rats may be associated with the increase of HSP70 synthesis.