Cisplatin incorporated into polylactic acid/polyethylene glycol acid blend polymeric microspheres was prepared as a dosage (CDDP-MS) by solvent evaporation method in oil-in-oil emulsion system. CDDP-MS and CDDP aqueous solutions (CDDP-SOL) were intraperitoneally administered to compare the tissue distribution of CDDP in 72 rats each. On 0.5, 1, 7, 14, 21 and 30 days, the omentum, lung, liver and kidney were removed, and the CDDP concentration was measured. The CDDP concentration of CDDP-MS group was maintained at a high level in the omentum for a long time. On the other hand, the CDDP level of the CDDP-MS group was low in the lung, liver and kidney, compared with the CDDP-SOL group. Additionally, acute toxicity of anticancer drug in CDDP-MS group was reduced, compared with CDDP-SOL. The effects of CDDP-MS, CDDP-SOL, empty-MS and non-therapy group on survival time were compared using intraperitoneally administered Yoshida sarcoma. The survival time in CDDP-MS, CDDP-SOL, non-therapy and empty-MS group were 43 +/- 24, 11.7 +/- 4.7, 9.8 +/- 1.1, and 7.8 +/- 1.1 days each. Consequently, it was suggested that CDDP-MS is useful as a tool in loco-regional chemotherapy using drug delivery system.