Studies on the drug release in vitro and hepatic arterial chemoembolization in vivo were carried out with the newly developed CDDP-PLA microspheres. The mechanism of the in vitro release was shown to conform to Higuchi equation. After chemoembolization the CDDP-PLA microspheres showed remarkably lower CDDP concentrations in the general circulation and much higher concentrations in the hepatic tissue e. g. up to 21.55 +/- 12.18 micrograms/g at 8 h, which is much higher than that (3.16 +/- 0.09 micrograms/g) of the CDDP in hepatic arterial infusions. Thus, the CDDP-PLA microspheres may improve the curative effects and lower the side effects, especially the kidney toxicity, of the anticancer drug cisplatin.