The rate and extent of absorption of a drug affect the onset, duration and intensity of the pharmacologic response. The most important factors that influence the absorption of rifampicin from the gastro-intestinal tract are the crystal form, the particle size, capsule formula and manufacturing process. We studied the bioavailability of rifampicin from Chong Kun Dang and from foreign world-wide company. Single oral dose of 600㎎ rifampicin as capsules was administered to six volunteers in fasting conditions according to crossover design. Results of test are as following.