PURPOSE: There has been debate on the use of peritoneal irrigation and drainage following gastric cancer surgery. This study was conducted to evaluate the usefulness of routine peritoneal irrigation and drainage following gastric cancer surgery, especially with regard to the perioperative leukocyte count. METHODS: Of 298 patients, 153 were enrolled in the test group (without peritoneal irrigation & drainage), between October 2001 and August 2002, and 145 in the control group (with peritoneal irrigation and drainage), between January 2001 and September 2001. The demographics, range of dissection, pathological staging, operation times, anesthesia times, fever, perioperative leukocyte counts and operative complications were retrospectively analyzed in these consecutive patients. RESULTS: It was found that there was no difference in the demographics, range of dissection, pathological staging and operative complications between the two groups. However, the operation times, anesthesia times, and mean length of hospitalization in the test group were significantly shorter than those in the control group. No significance differences were found between the two groups with regard to the perioperative leukocyte counts. CONCLUSION: The routine usage of peritoneal irrigation and drainage was found to be neither safe nor effective in gastric cancer surgery patients.