Glutathione (GSH) is a crucial antioxidant and redox signaling molecule present in all mammalian tissues. It plays vital roles in detoxification, cell proliferation, apoptosis, immune function, and fibrogenesis. The biosynthesis of GSH occurs in the cytosol and is regulated by the availability of cysteine and the activity of glutamate-cysteine ligase (GCL), which consists of a catalytic (GCLC) and a modifier (GCLM) subunit. GSH synthetase (GS) is the second enzyme involved in GSH synthesis. Key transcription factors regulating GSH synthesis include Nrf2 via the antioxidant response element (ARE), AP-1, and nuclear factor kappa B (NfκB). Dysregulation of GSH synthesis has been linked to various pathological conditions, including diabetes, pulmonary and liver fibrosis, alcoholic liver disease, cholestatic liver injury, endotoxemia, and drug-resistant tumors. Understanding the regulation of GSH synthesis and its dysregulation in disease states may lead to improved treatments for these disorders.Glutathione (GSH) is a crucial antioxidant and redox signaling molecule present in all mammalian tissues. It plays vital roles in detoxification, cell proliferation, apoptosis, immune function, and fibrogenesis. The biosynthesis of GSH occurs in the cytosol and is regulated by the availability of cysteine and the activity of glutamate-cysteine ligase (GCL), which consists of a catalytic (GCLC) and a modifier (GCLM) subunit. GSH synthetase (GS) is the second enzyme involved in GSH synthesis. Key transcription factors regulating GSH synthesis include Nrf2 via the antioxidant response element (ARE), AP-1, and nuclear factor kappa B (NfκB). Dysregulation of GSH synthesis has been linked to various pathological conditions, including diabetes, pulmonary and liver fibrosis, alcoholic liver disease, cholestatic liver injury, endotoxemia, and drug-resistant tumors. Understanding the regulation of GSH synthesis and its dysregulation in disease states may lead to improved treatments for these disorders.