A new medical system was started in Korea in 2000 and pharmaceutical affairs law was revised in 2001. According to the revised law, generic substitution is permitted only to the drug products which are proven to be bioequivalent to the reference listed drugs. To expand the list of bioequivalence-proven drug products and to ensure the credibility of the therapeutic equivalence of generic drug are the hot issues in Korea. Also, the KFDA has a plan to revise the pharmaceutical affairs law that bioequivalence reports of all the generic prescription drug products should be submitted to the KFDA for drug approval after July in 2004. Therefore, it is increasing the necessity to develop the bioequivalence-demonstrating methods for specific drug substances and preparations which require to conduct food-effect bioavailability or bioequivalence study. There are some differences between US and Japanese guidances of food-effect bioavailability and bioequivalence studies. In this paper, we examined the recently published US guidance about food-effect study and it will be a reference to make our own guidance about food-effect bioavailability and bioequivalence guidances in Korea.