In this report, we discuss a case of obscure gastrointestinal bleeding (OGIB) in an 18-year-old man, where oesophagogastroduodenoscopy (OGD) and colonoscopy proved inconclusive in determining a source of bleeding. On day 14 of admission, a laparoscopy was performed, identifying a mass 2 feet from the ileocaecal junction. This was thought initially to be a Meckel's diverticulum and the patient underwent a laparotomy and a small bowel resection. Surprisingly, the histology revealed a benign gastrointestinal stromal tumour (GIST) of the ileum, rare in such a young person. Given the diagnostic delay, we propose a simple algorithm for the diagnostic management of a teenager presenting with a significant ongoing gastrointestinal bleed.