The effects of components of the medium on the production of extracellular polysaccharide (EPS) by cultured cells of Polianthes tuberosa (tuberose) were studied. Optimization of media components culturing in flash resulted in increasing EPS production from 1.4 to 4.1 g/l. In particular, relatively high concentration (10(-5)M) of 2,4-dichlorophenoxyacetic acid (2,4-D) markedly stimulated the production of EPS. Based on these results, EPS production by a 30-1 jar fermenter was attempted and the final rate of production was 4.6 gn at 30th day of culture. The EPS consisted mainly of acidic polysaccharides with glucuronic acid, mannose, arabinose, galactose, glucose and xylose.