To investigate the possible mechanisms of nobiletin for anticancer by studying the inhibition effects of nobiletin on tubulin polymerization.In vitro nobiletin was added into the tubulin polymerization-depolymerization system and the absorption values were recorded at 350 nm under 37 degrees C.As compared with controls, the absorption values in reaction system decreased significantly in nobiletin treatment groups. When nobiletin final concentrations in reaction system were 5.0, 7.5, 10.0 and 12.5 micromol x L(-1), the maximum absorption values were 0 130, 0.109, 0.086 and 0.071 with 16.7%, 30.1%, 44.9% and 54.5% of inhibition rate, respectively. The results suggested that nobiletin could inhibit tubulin polymerization.The inhibition effect of nobiletin on tubulin polymerization is the possible mechanism for anticancer.