OBJECTIVE To examine the ultrastructure of gastric cancer cells by the electron microscope, in order to assess the relationship between neuroendocrine differentiation and post-operative survival time.METHODS NSE, Syn and CgA immunohistochemical labeling was conducted in 168 cases with a common-type of gastric cancer. Electron microscopy was performed in 80 cases with positive immunohistochemical labeling.These cases were followed-up for over 5 years and the post-operative survival data analyzed.RESULTS Neuroendocrine granules were found by electron microscopy in 39 cases. The rate of neuroendocrine differentiation found was 23% (39/168), using routine diagnostic criteria and electron microscopy (REM).The post-operative survival time of gastric cancer patients with neuroendocrine differentiation was significantly shorter (P=0.0032) compared to those without neuroendocrine differentiation.CONCLUSION It is of significant clinical importance to determine if the neuroendocrine cells are differentiated in gastric cancers. The gastric cancer patients with neuroendocrine differentiation have a shorter post-operative survival time and a poorer prognosis. Electron microscopy is a reliable method of providing a diagnosis.