Nucleic acid aptamers are molecules that are being used in a large number of biomedical applications. Aptamers have the properties to bind to a wide range of molecules with high specificity and affinity for their target. These properties together with their small size and their ease of synthesis make them very attractive and promising for targeting diseases and therapeutic applications. Aptamers can serve as cancer diagnostic tools by detecting specific biomarkers, circulating cancer cells or imaging diseased tissue. On the other hand, aptamers can be used as therapeutic agents due to their potential antagonist activity, or as targeting agents. Therefore, they can be designed to deliver antitumor molecules such as chemotherapeutic drugs, siRNA or photodynamic therapy sensitizers to diseased tissues. Attempts are also made to synthesize aptamers-targeted nanoplatforms capable to ferry cargo and load onto them both imaging and therapeutic functions creating so called nanotheragnostics agents. In the future, its seems likely that aptamers will play an important role in diagnosis and treatment of several pathologies including cancer.