Abstract: OBJECTIVE To study the effects of tanshinoneⅡA on the pharmacokinetics of theophylline in rats. METHODS A total of 24 rats were randomly divided into three groups: Group Ⅰ(the same volume of saline, ip×7 d), Group Ⅱ(tanshinoneⅡA 7 mg·kg^-1·d^-1, ip×7 d) and Group Ⅲ(tanshinoneⅡA 20 mg·kg^-1·d^-1, ip×7 d). The 3 groups were given a single dose of 20 mg·kg^-1·d^-1 aminophylline with intragastric administration after intraperitoneal injection for 7 d. Blood samples were collected from the tail vein before administration and at 0.17, 0.33, 0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0, 10.0 and 12.0 h points after administration. The concentration of theophylline in plasma was detected by HPLC method. The pharmacokinetic parameters were analyzed by DAS program. RESULTS After administration, the main pharmacokinetic parameters of theophylline for Group Ⅰ were as follows respectively: C_max was (29.43±1.53)mg·L^-1, AUC_0→∞ was (156.95±10.22)mg·h·L^-1, MRT_0-∞ was (4.44±0.42)h, CLz/F was(0.13±0.01)L·h^-1·kg^-1. Compared with Group Ⅰ, there was no significant difference in the pharmacokinetic parameters of theophylline for Group Ⅱ, but the AUC_{0→12 h}, AUC_0→∞, C_max, MRT_0-t, MRT_0-∞, CLz/F of theophylline for Group Ⅲ were a significant difference(P<0.05). The C_max and AUC_0→∞ of theophylline for Group Ⅲ decreased 7.54% and 14.69%, respectively and the CLz/F was increased 23.08%. CONCLUSION The higher dosage of tanshinoneⅡA affects the pharmacokinetics of theophylline in rats, while the lower dosage does not.