Studies on the production of exopolysaccharide(EPS) in submerged cultures of Schizophyllum commune mycelium has been carried out. At the same time, we also investigated the possibility of the simultaneous accumulation in the culture broth of pinitol, an antidiabetic agent contained in a specific component (carob) of the production medium. For the purpose of optimizing fermentation conditions for the enhanced production of EPS together with maximal accumulation of the antidiabetic agent, carbon/nitrogen ratio(C/N ratio), KH₂PO₄ concentration, and  inoculum size were intensively investigated in both shake-flask and bioreactor(5L) cultures. C/N ratio was found to have the most significant effect on the EPS biosynthesis, with the maximal EPS production of 8g/L at the C/N ratio of 20:1(i.e. glucose plus yeast extract vs. soytone peptone = 20:1). Disappointingly, however, at the C/N ratio of 20:1 above, a small amount of unmetabolized fructose was found to still remain in the fermentation broth, even though the antidiabetic agent was effectively concentrated in the fermentation broth. This phenomenon, which made it somewhat difficult to separate the antidiabetic agent from the fermentation broth, was successfully overcome by adopting a fed-batch fermentation process, resulting in a complete consumption of the residual fructose left in the batch operation process above.