Since irinotecan, S-1, docetaxel, and paclitaxel were approved, therapeutic options for chemotherapy in the treatment of gastric cancer have increased. It is suggested that the efficient use of the primary drugs prolongs life in the treatment of progressive colorectal cancer. Also, physicians have discussed ways to take full advantage of the drugs in the treatment of gastric cancer. In first-line treatment in other countries, combination therapy usually includes the administration of two drugs, while in Japan, where therapies based on S-1 have been developed, the most appropriate strategy must be determined after reporting the results of phase III trials in 2007. In the clinic, treatment must be selected on the basis of solid evidence in consideration of the organ dysfunction associated with progressive gastric cancer. The timing of any changes in the treatment should be considered because the cancer easily metastasizes to the peritoneum. Throughout the world, various regimens have been developed that replace cisplatin with oxaliplatin or mainly use oral fluoropyrimidine. Molecular target drugs, now being evaluated in phase II trials, will also be used in the treatment of gastric cancer in the near future. Novel therapies will be developed in Asia and Japan where the incidence of gastric cancer is high.