The number of elderly persons is rapidly increasing worldwide. Most of the cancer patients are diagnosed at 65 years and older. In elderly patients, because of age related physiologic changes. pharmacokinetic and pharmacodynamic properties of chemotherapy agents have some differences from these of young patients. Generally. there is a tendency of under treatment the older patients with cancer, Several studies has been shown that elderly patients can obtain similar benefits from treatment and the toxicity rates were not more than young patients. Before decision of cancer treatment plan, comprehensive geriatric assessment including functional test and laboratory evaluation should be done to determine life expectancy and functional reserve. In this review, we evaluated that age related physiologic changes and their effects on cancer treatment and analyzed treatment strategies of more frequent cancer types in elderly patients.