The article discusses the dual role of transforming growth factor-β (TGF-β) in tissue repair and its potential pathogenic effects in various diseases. TGF-β is a multifunctional cytokine crucial for embryonic development and tissue repair, promoting healing by attracting immune cells, inducing angiogenesis, and regulating other cytokines. However, excessive TGF-β action can lead to tissue damage and scarring in diseases such as glomerulonephritis, diabetic nephropathy, and fibrotic conditions in other organs. The authors propose that the pathological consequences of excessive TGF-β action be termed the "dark side" of tissue repair. They highlight studies demonstrating that elevated TGF-β levels are associated with increased extracellular matrix production and fibrosis in these conditions. Additionally, they discuss the immunosuppressive effects of TGF-β and its potential therapeutic applications, including the use of TGF-β inhibitors to control fibrotic diseases. The article emphasizes the need for further research to understand and manage the balance between the beneficial and harmful effects of TGF-β in tissue repair.The article discusses the dual role of transforming growth factor-β (TGF-β) in tissue repair and its potential pathogenic effects in various diseases. TGF-β is a multifunctional cytokine crucial for embryonic development and tissue repair, promoting healing by attracting immune cells, inducing angiogenesis, and regulating other cytokines. However, excessive TGF-β action can lead to tissue damage and scarring in diseases such as glomerulonephritis, diabetic nephropathy, and fibrotic conditions in other organs. The authors propose that the pathological consequences of excessive TGF-β action be termed the "dark side" of tissue repair. They highlight studies demonstrating that elevated TGF-β levels are associated with increased extracellular matrix production and fibrosis in these conditions. Additionally, they discuss the immunosuppressive effects of TGF-β and its potential therapeutic applications, including the use of TGF-β inhibitors to control fibrotic diseases. The article emphasizes the need for further research to understand and manage the balance between the beneficial and harmful effects of TGF-β in tissue repair.