Abstract: Objective:To investigate the suppressive effect of oligochitosan (6-9 chitosan molecules) on ascites tumor andsolid tumor. Methods: (1) By in vitro incubation of ascites tumor cells, investigating the suppressive effect of oligochitosan onthe tumor cell growth .(2) By feeding with different doses of oligochitosan and transplanting cancer cells-solid tumor andascites tumor to the mice respectively, observing lifetime and investigating in vivo suppressive effect of oligochitosan.Results:Oligochitosan could suppress DNA synthesis of the incubated ascites tumor .After feeding oligochitosan for 30 days, thelifetime of the medium dose group (280mg/day/kg.bw) and the high dose group (840mg/day/kg.bw) of the solid tumor trans-planted mice stayed significantly longer incomparison with that of the control mice (p<0.01).And the tumor weight of themice borne solid tumor was significantly lower than that of the control (p<0.05). Conclusion: The oligochitosan could suppressthe ascites tumor and solid tumor to a certain degree.

Key words: Oligochitosan , Suppression of tumor , Ascites tumor , Solid tumor.