Although much progress has been made in treating cancers, cancer death rates in and around the United States are still high. Current treatments are either ineffective against some cancers or detrimental to patients, which decreases their quality of life. The use of nanotechnology in cancer therapy can potentially increase patient survival, reduce side effects, and reduce mortality rates because nanoparticles (NPs) have the potential to target only tumors and bypass healthy cells. NPs possess many features, including size, shape, charge, and composition, which allow them to carry chemotherapeutics to cancer cells. NPs can also be used in radiotherapy as radiosensitizers and in imaging as contrast agents. Many studies have performed in vitro and/or in vivo experiments on these particles in human and animal cell lines. This review discusses recent studies on different NPs and their potential use in cancer therapy.