This case report demonstrates successful endoscopic treatment of a persistent gastrocutaneous fistula after removal of a percutaneous endoscopic gastrostomy (PEG) in a 21-year-old patient with mucoviscidosis after lung transplantation. Because the initial OTSC clip (gastric) did not close the fistula sufficiently, we had to remove it and replace it with a larger OTSC clip (colon) in a second intervention. That clip finally sufficiently closed the fistula.