From July, 2007 to June, 2008, we prospectively investigated the influence of Hange-shashin-to on the therapeutic and adverse effects of chemotherapy and the changes in quality of life(QOL)scores of the patients with metastatic gastric and colorectal cancer. Twenty patients receiving S-1/Irinotecan (CPT-11) therapy were randomly allocated into group A (with Hange-shashin-to) and B (without Hange-shashin-to). While the anti-tumor effects did not differ significantly between these two groups, severe side effects of more than grade 3 occurred less frequently in group A. Our results suggested that the decrease in QOL scores on day 15 might be alleviated in group A, compared to group B. Therefore, Hange-shashin-to can be one of the useful supportive medicines in the combination therapy of S-1/CPT- 11.