Chyloperitoneum, also called chylous ascites, is a rarely reported complication of abdominal surgery. In most cases, the diagnosis and treatment is not difficult. The characteristic milky colored odorless fluid is easily detected by drainage or aspiration. With the help of diagnostic radiology and laboratory tests, it has become easier to detect the chyloperitoneum. Chyloperitoneum subsides spontaneously or responds well to medical treatment. Death from chyloperitoneum is extremely rare. However, 3 cases of medically intractable chyloperitoneum were encountered at our hospital after curative surgery for gastrointestinal malignancies (two colorectal cancers and one gastric cancer). Herein, the authors report these case and discuss their treatments.