RNA therapeutics, a new class of medication based on RNA molecules, is utilized in treating and preventing human diseases. RNA therapeutical strategies involve the use of both coding RNA (messenger RNA, mRNA), and non-coding RNA (small interfering RNA, siRNA; antisense RNA, asRNA; interference RNA, RNAi, and RNA aptamers). RNA therapeutics was first developed in the 1960s and then it has become an indispensable technology in producing RNA-based molecular products, including RNAs inhibiting other RNA activities, RNAs targeting proteins, RNAs reprograming genetic information, and RNAs encoding therapeutical proteins. In particular, siRNA therapeutics were applied in treating various human cancers, chronic viral infections, and other diseases such as acute kidney injury and beta-thalassemia. On the other hand, mRNA therapeutics can be used as safe and effective vaccines for infectious diseases, such as the coronavirus disease in 2019 (COVID-19) caused by the severe respiratory syndrome coronavirus 2 (SARS-CoV-2). RNA therapeutical development requires several significant difficulties, such as the rapid degradation of exogenous RNA, the delivery of negatively charged RNA, and the potent immunogenicity of exogenous RNA that causes cell toxicity and impaired translation into therapeutic proteins. Therefore, until recently, there is few RNA therapeutics have been approved for public use by the United States Food and Drug Administration (USFDA), such as Pegaptanib in 2006, Patisiran in 2018, Givosiran in 2019, BNT162b1 and mRNA-1273 in 2021. In this Volume, we discuss the relevant aspects of up-to-date RNA therapeutics, e.g., RNA drug targets, RNA biochemical analysis, RNA therapeutical applications in clinics, current RNA therapeutical strategies, etc.