TNAs, or therapeutic nucleic acids, are nucleic acids or closely related compounds that are used to cure disease. TNAs come in a variety of shapes and sizes, but they all have the same mode of action: sequence specific recognition of endogenous nucleic acids via Watson–Crick base pairing. The growing number of FDA-approved nucleic acid therapies shows that diseases can be treated in vivo by addressing their genetic blueprints. Because they target proteins rather than the underlying reasons, traditional therapies typically have transitory therapeutic results. Nucleic acid treatments, on the other hand, can achieve long-lasting or even curative effects by inhibiting, replacing, or altering genes. However, delivery strategies that improve stability, enable internalisation, and boost target affinity are required for clinical translation. Synthetic biology, systems biology, computational biology, bioinformatics, and nanotechnology, among other fields, have accelerated progress and established a new paradigm for nucleic acids in therapy.