For the purpose of development of a supercritical process, controlling the shape and size of the pharmaceutical products, we performed experiments on the RESS process preparing griseofulvin fine particles. Supercritical fluid was CO2, and orifice disk and capillary nozzle were adapted as expansion devices. Besides leaching temperature and pressure, which are the major operating parameters for the commom researches in RESS process, we examined the effect of crystallization media and introduction of hot N2 stream to the crystallization unit on the shape and size of griseofulvin fine particles. When supercritical griseofulvin solutions were expanded into aqueous solution, size and crystallinity of the particles increased compared to those expanded into atmoshere. Our results showed that very fine griseofulvin particles could be obtained by introducing hot N2 stream to the atmospheric crystallization unit.