This collection opens with a focus on recent advancements on the development of nucleic acid aptamers as alternative delivery systems for therapeutic oligonucleotides. Additionally, key examples of targeted delivery of the most common nucleic acid therapeutics, including small interfering RNAs, short hairpin RNAs, microRNAs and antisense oligonucleotides for a number of disorders are discussed. The following chapter deals with in vivo studies that were conducted with radiopharmaceuticals based on aptamers, the radionuclides used, the radiolabeling strategies, the chemical modifications of interest to improve their properties, and the main aptamers advantages and drawbacks for application as radiopharmaceuticals. In conclusion, the authors discuss the perspectives of using aptamers in various detection methods, their advantages and disadvantages, and the results of such work carried out through the present day.