The incidence and prevalence of most cancers increase with age. The immune system is a unique mechanism of defense against pathogens and possibly cancers, however there is a body of evidence that the immune system of the aged is eroded, a phenomenon termed immunosenescence. Each arm of the immune system, innate and adaptive, is altered with aging, contributing to increased tumorigenesis. Related to immunosenescence, a low-grade inflammation also develops with aging contributing also to increase carcinogenesis. Understanding the contribution of immunosenescence to cancer development and progression may lead to better interventions in the elderly.