OBJECTIVE： To compare the difference of the information about smoking affecting pharmacodynamics and pharmacokinetics in prescription drug instructions between US and China. METHODS： The US and Chinese guidance for drug R&D and drug instructions editing， prescription drug instructions were collected； the information about smoking affecting pharmacodynamics and pharmacokinetics were retrieved from FDA drug instruction official website DailyMed and Yaozhi Network in China up to Jun. 19th， 2014. The difference in related regulations and drug instruction were compared between US and China. RESULTS & CONCLUSIONS： The guidance issued by US and China require that great importance should be attached to the effects of smoking on pharmacodynamics and pharmacokinetics， and it must be noted in drug instructions. Of 62 857 drugs recorded， smoking affected pharmacodynamics and pharmcokinetics of 34 drugs in US drug instructions， among which 9 drugs needed dose modifications； for above drugs， Chinese drug instructions pointed out great importance should be attached to the effect of smoking on pharmacodynamics and pharmacokinetics of 6 drugs， and only one drug （erlotinid hydrochloride） needed to be modified. The label rate of smoking affecting pharmacodynamics and pharmacokinetics was relatively low in Chinese drug instructions compared to US. It is suggested that the regulatory agent should standardize and improve related description in drug instruction， correct unsuitable content， revise the items which may result in severe consequence， and set up official website which can provide all drug instructions as soon as possible. Drug manufacturers should standardize clinical study of drugs before marketing， focus on the scientificity， completeness and normalization of drug instructions.