The ability of immune system to detect and destroy the altered/abnormal cells may inhibit the development of various cancers. The immune system had been proposed as a tactic in sustaining nonneoplastic state and also for the development of immunotherapy against cancer. Although the immune system exerts a protective role, under certain circumstances, it could be damaging in terms of modulating the oncogenic process. The failure of host's immunological responses against tumor growth and dissemination implicated that both immunologic and nonimmunologic factors may work together to affect tumorigenesis. Hence, understanding the aspects pertaining to tumor immunology which deals with the complex interactions between the host's immune system and neoplasm is essential. The current review focuses on the aspects concerned with tumor immunology, steps involved, and cancer immunotherapy as a probable therapeutic tool.