AIM: To develop a GC MS method for the study of pharmacokinetics of aspirin and salicylic acid in healthy human volunteers. METHODS: A 25 m×0 2 mm ID capillary column was used. The carrier gas was helium. Benzene carbonic acid was used as internal standard. The plasma was extracted with ether—dichloromethane (4∶1) after adding 3 mol·L -1 HCl and then reacted with bis (trimethylsilyl) trifluoroacetamide (BSTFA). The concentrations of aspirin and salicylic acid were measured by GC MS (SIM). The pharmacokinetic parameters were computed using 3P87 program. RESULTS: A good linearity was obtained from 2 0～400 ng·mL -1 of aspirin and 0 2～10 0 μg·mL -1 of salicylic acid in human plasma. The detection limit of aspirin and salicylic acid were 1 0 ng·mL -1 and 0 1 μg·mL -1 in plasma, respectively. The results showed that the plasma concentration time courses conformed to one compartment model following a single oral dose of 50 mg aspirin tablets given to each of the 8 volunteers. CONCLUSION: The established GC MS method was a good method for determination of aspirin and salicylic acid in human plasma. The method was simple, precise and sensitive.