A medicinal mushroom Fomes fomentarius, was isolated from the fruiting body of a wild F. fomentarius and identified by ITS-5.8S rDNA sequencing analysis. Then, the optimization of submerged culture conditions and nutritional requirements of mycelial biomass and exopolysaccharide (EPS) production from F. fomentarius was studied using orthogonal matrix method. Under the optimal culture condition, the maximum EPS concentration reached 3.64 g l(-1), which is about four times higher than that at the basal medium. Furthermore, the EPS from F. fomentarius has a direct antiproliferative effect in vitro on SGC-7901 huaman gastric cancer cells in a dose- and time-dependent manner. Moreover, it was about three times that EPS at noncytocxity concentration of 0.25 mg ml(-1) could sensitize doxorubicin(Dox)-induced growth inhibition of SGC-7901 cells after 24h treatment.