Stomach cancer is the fourth most common malignancy worldwide. Endoscopy (with biopsies) is the gold standard for its diagnosis but missed oesophageal and gastric cancers are not infrequent in patients who have undergone previous endoscopy. Errors by the endoscopist account for the majority of these missed lesions. The following report describes an incident in which there was a diagnostic error that led to a failed diagnosis of gastric cancer at first endoscopy. The implications for clinical and endoscopic practice are discussed.