Hidden pain in the right upper part of the stomach may be caused by gastritis, myocardial infarction, gastric cancer and other factors. 1. Gastritis: when inflammation occurs in gastric mucosa, inflammatory cells in the body may release inflammatory mediators when stimulated, which include some pain-causing substances, and under the action of these substances, vague pain in the upper right side of the stomach may occur. 2. Myocardial infarction: In myocardial infarction, local myocardial tissues may be necrotic due to ischemia and hypoxia, and under the stimulation of necrotic substances, it may cause vague pain in the right upper part of the stomach. 3. Gastric cancer: gastric cancer is a malignant tumor of stomach, with the continuous growth of tumor cells, it may invade the stomach wall. Since visceral pain has the feature of inaccurate localization, therefore, vague pain in the right upper part of stomach may also appear in the case of gastric cancer. When there is vague pain in the right upper part of the stomach, it is recommended to consult doctor in time, and complete gastroscopy, electrocardiography, tissue biopsy and other tests under doctor’s guidance to clarify the cause of disease and treat it actively.