A 59-year-old male with chronic kidney disease was diagnosed as having advanced gastric cancer(cT2N1P0H1M0), and CPT-11+CDDP therapy was started for him simultaneously with hemodialysis(HD). Serum CDDP concentrations were measured in the 1st course, and free-platinum(f-Pt)showing the anti-tumor effect was found to be eliminated by HD. Serum f-Pt levels, however, re-elevated until 24 hours after HD completion. Serum concentrations measured in the 15th course showed that f-Pt levels became higher than those observed in the 1st course, suggesting that CDDP was not completely removed by HD. Medical treatment was continued until the liver metastases were judged to be a progression disease at completion of the 18th course. When CDDP was administered to patients on HD, it was necessary to pay attention to various CDDP serum concentrations, and to tailor the dose to a tolerable level in each patient. Such an individual therapy might enable CPT-11+CDDP therapy to be one of the medical treatments of choice for advanced gastric cancer patients on HD.