Endoscopic biopsy is thought to be the best method to obtain biopsy samples of the gastrointestinal tract. In our case, however, an endoscopic forceps biopsy failed to confirm malignancy of an intramural gastric tumour. Since the tumour, about 4 cm in diameter, was well delineated on the CT scan, the patient was referred for a percutaneous CT-guided needle biopsy, which confirmed a gastrointestinal stromal tumour.