OBJECTIVE To study the pharmacokinetics of tetramethylpyrazine (TMP), ferulic acid and their compatibility. METHODS Twenty-four Sprague-Dawley rats were randomly divided into 3 groups: TMP 20 mg x kg(-1), ferulic acid 20 mg x kg(-1) and TMP 20 mg x kg(-1) + ferulic acid 20 mg x kg(-1). All the rats were given intragastric administration then blood samples were obtained from fossa orbitalis at several time points. All the plasmas concentrations were analyzed by HPLC method and the data were treated by DAS 2.0 program. RESULTS The main pharmacokinetics parameters of TMP 20 mg x kg(-1) group, ferulic acid 20 mg x kg(-1) and TMP 20 mg x kg(-1) + ferulic acid 20 mg x kg(-1) were as follows: t(max) 0.5 h, t1/2 0.856 h,MRT 1.321 h, AUC 5.112 microg x h(-1) x L(-1), C(max) 2.834 microg x L(-1); t(max) 0.083 h, t1/2 1.024 h, MRT 1.324 h, AUC 1.581 microg x h(-1) x L(-1), C(max) 1.492 microg x L(-1); t(max) 0.583 h, t1/2 37.901 h, MRT 3.798 h, AUC 4.097 microg x h(-1) x L(-1), C(max)1.571 microg x L(-1); t(max) 0.6 h, t1/2 7.860 h, MRT 2.894 h, AUC 1.984 microg x h(-1) x L(-1), C(max) 1.03 microg x L(-1), respectively. CONCLUSIONS The experiments suggested that the compatibility of TMP and ferulic acid had interaction in pharmacokinetics; all the t1/2 and MRT were prolonged and had the effect of lente liberates.