In Korea, generic drug and bioequivalence test are the hot issues since a new medical system of separation of dispensary from medical practice was started in 2000. The KFDA(Korea FDA) had revised several times ${ulcorner}Guidance;for;bioequivalence;test{lrcorner}$. In vitro dissolution test has been extensively used as a quality control tool for solid oral dosage forms. In an effort to minimize unnecessary human testing, in vitro/in vivo correlations (IVIVC) between in vitro dissolution and in vivo bioavailability are increasingly becoming an integral part on extended release drug product development. The recently published US guidance, ${ulcorner}Extended;release;oral;dosage;forms;:;development,;evaluation,;and;application;of;in;vitro/in;vivo;correlations{lrcorner}$ will be helpful for us to make our own guideline.