As synthetic oligonucleotides with high affinity and selectivity, aptamers have an outstanding potential for medical diagnosis and treatment. This manuscript enquires into the generation, characteristics and applications of aptamers. The role of aptamers in medicine is also discussed. The study shows that aptamers stand as great candidates in medical sciences for development of biosensors and targeted drug delivery systems because of their unique properties such as high affinity and selectivity towards their targets, inexpensiveness and in vitro synthesis, high stability, and small size.