Streptozotocin has been used to induce diabetes mellitus in experimental animals and has been thought to have a selective cytotoxic effect on the beta-cells in the islets of Langerhans. The aim of the present study was to determine whether streptozotocin has any cytotoxic effect on other neuroendocrine cells of the gastrointestinal tract. Eight female Sprague-Dawley rats received intraperitoneal injections of 100 mg/kg streptozotocin in citric acid buffer; the concentration of streptozotocin was adjusted to 25 mg/ml buffer. Seven rats, serving as controls, received an equivalent volume of the vehicle. The rats were killed after three days and the fundus, antrum, small intestine and pancreas were examined for neuroendocrine cells. Our study confirms that streptozotocin is cytotoxic towards beta-cells. In addition, it is cytotoxic towards neuroendocrine cells of the oxyntic mucosa of the stomach. This finding may have clinical significance and suggests that streptozotocin may be used in the treatment of gastric neuroendocrine tumors as well as insulinomas.