AIM To evaluate the pharmacological effect of phosphorus-32 glass microspheres (32p-GMS) injected intothe implanted human liver cancer cell mass in nude mice.METHODS Fifty-two Balb/c tumor loaded nude mice were allocated into treatment group (n =38) andcontrol group (n = 14), in the former group different doses of 32p-GMS were injected into the tumor mass,while in the latter group 31 P-GMS or no treatment were given instead of 32 P-GMS. After dynamicallyobserving the growth of tumor for d 3 - d 28, the experimental animals were killed in batches, the tumor andits nearby tissues were examined by light and electronic microscopy.RESULTS In comparing with the control group, the treatment group showed the tumor inhibiting rates of59.7% -93.6% (Variance analysis of the mean weight of different doses and control group after square rootcorrection, F= 579.62, P