AbstractFeruloyl oligosaccharide 1 (FO1) and feruloyl oligosaccharide 2 (FO2) were produced from wheat bran fermented by Aureobasidium pullulans (A. pullulans) through one- and two-stage temperature and pH controlling processes, respectively. Here the anti-tumor and immunostimulatory functions of FO1 and FO2 were further examined. Both FO1 and FO2 inhibited the growth of cancer cells but were non-toxic to normal cells in vitro. In S180 tumor-bearing mice, both FO1 and FO2 significantly inhibited the growth of transplanted tumors and promoted thymus, spleen indexes, interferon-γ, and interleukin-3 production. They also increased peripheral leukocyte count and bone-marrow cellularity. The biological activity of FOs prepared by different processes was further determined. Interestingly, FO2 possessed more potent anti-tumor and immunostimulatory effect than FO1 in a dose-dependent manner. At a dose of 250 mg/kg, the tumor inhibition rates for FO1 and FO2 were 22.42% and 44.85%, respectively. These antitumor properties of FOs may be mediated by their beneficial effects on immunity responses. These data suggest that FOs from wheat bran may be used as anti-tumor agents in the future.