We have observed an adenocarcinoma of the stomach which developed on the site where an apparently benign active gastric ulcer had been diagnosed radiologically 10 and 7 years previously. The patient had complained of recurrent episodes of epigastric pain over ten years, which were well controlled by the medical treatment. The length of clinical history in this patient makes it unlikely that his ulcer was neoplastic at the time of onset. This appears to be, therefore, one of the rare instances of development of a gastric carcinoma on the site of a previously benign peptic ulcer.