Thiol-containing compounds are central actors in many biochemical and pharmacological reactions. The response of cells to any stress (including cell division and apoptosis) involves changes in thiol content as they are consumed to protect cells via different actions (direct modification / regulation of biomolecules, antioxidativity, detoxification, signal transmission). The story of glutathione, the basic intracellular thiol-containing compound, ranges throughout different scientific fields. The importance of this biomolecule is highly impressive. Reduced glutathione (GSH) is a principal actor in many physiological and pharmacological reactions. There are about 60 000 entries under “glutathione” found in the Medline database. The aim of this short review is to characterize glutathione and show that due to an intriguing and multifaceted biofunctionality in the human body this tripeptide itself, as well as its analogues, belongs to the group of molecules looking for broad clinical use (besides being excellent antioxidants). This information might draw more attention to the discovery and investigation of glutathione system supporting / relating substances with a substantial clinical impact.