The historical background, pharmacological effects, significance as modulation therapy and clinical results of chemotherapy combining 5-FU/cisplatin or UFT/cisplatin based on the concept of biochemical modulation are introduced and reviewed. The evident significance of this method among various chemotherapies are its stable maintenance of the effective concentration of 5-FU and the outstanding anticancer efficacy at the clinical level. However, an optimal administration method has not necessarily been established to date. The concentrations and duration of anticancer effects and side effects for each drug remain to be studied. By resolving these problems, this optimal administration method (both the route and duration) may be clarified. Anything compromising patient quality of life, of course, must be prevented. The above gives the basis of our recent experience. We considered it an effective combination therapy and expect that numerous trials at various centers will lead to improvements.