Two patients received intraperitoneal cisplatinum chemotherapy for carcinomatous ascites due to colorectal cancer recurrence. The patients were a 47-year-old man who had rectal cancer and 51-year-old woman who had colon cancer. They had received the operation and adjuvant chemoradiation therapy and chemotherapy respectively. However, five months and two years after resection, respectively, they presented massive ascites due to carcinomatous peritonitis and were given cisplatin injection intraperitoneally. The amount of ascites was significantly diminished. One patient had been discharged and been able to stay at home, and the other patient underwent gastrostomy for ileus. The results suggested that intraperitoneal cisplatinum chemotherapy may be useful for the patient with carcinomatous ascites due to colorectal cancer.