A case is described in which a patient with a gastrostomy tube (PEG) was admitted to hospital with chronic and severe diarrhoea and signs of cachexia. The gastrostomy tube had been inserted by percutaneous endoscopic procedure two months before, and the patient had been suffering from diarrhoea ever since. X-ray investigation by contrast documented that the PEG ended inside the colon, at the left colic flexure. The case emphasizes the need to control the position of a PEG, should unexpected gastrointestinal symptoms occur.