The interest in the detection and quantification of S-nitrosothiols or thionitrites RSNOs in biological media and their use as pharmaceutical agents is mainly related to the discovery of nitric oxide as an endothelium relaxing factor, and analytical methodologies that are able to detect these moieties in real time, in situ and ideally with high sensitivity and selectivity could help in a better understanding of their biological pathways. In this review, we discuss the performances of the electroanalytical strategies developed for the sensing of low molecular weight RSNOs in biological fluids.