Radiation therapy (RT) is an approved, most widely used strategy for the treatment and control of cancer progression but its successful application solely depends on the radiosensitivity of tumor cells and tolerance of normal tissue. To overcome this, very often radiation therapy is combined with radiosensitizing agents. Recently, due to the advancement in the field of nanotechnology, metal nanoparticles have been discovered as the novel radiosensitizers such as gold nanoparticles (GNPs). In contrast, some nanoparticles of noble metals like platinum nanoparticles (nano-Pts) act as radioprotectors and inhibit radiation-induced cell death. This review will summarize the latest findings on the 1) radiosensitizing effects of GNPs, 2) effects of platinum nanoparticles on inflammation and radiation-induced cell death.