Objective To evaluate the inhibitory effects of sustained-release 5-fluorouracil(5-FU)micmparticles on the growth of HepG2 eels.Methods The inhibitory effects of sustained-releage 5-FU micropartides,5-FU microparticles and poly L-lactic acid on HepG2 cells were detected by MTT assay.The HepG2 cell apoptosis was demonstrated by flow cytomerry after Hoehest staining.Results The survival rate of HepG2 cells in sustained-release 5-FU microparticles group decreased as time passed by.The survival rate of HepG2 cells in 5-FU microparticles group wag the lowest on the first day,and then it increased gradually.The survival rates of HepG2 ceHs in 5-FU microparticles group on day 21 and 28 were hJigher than those in sustained-release 5-FU microparticles group.The survival rate of HepG2 cells in poly L-lactic acid group WSB higher than that in the other two groups.The difference upon survival rate among the 3 groups had statistical significance(F=3163.52,128.47.P＜0.01).Conclusions The sustained-release 5-FU micropartieles could keep on inhibiting tlle growth and inducing apoptosis of HepG2 cells in time-dependant manner.The inhibitory effect of sustained-release 5-FU is better than that of 5-FU microparticles.