Right sternal pain is caused by the lesion of the chest wall tissue and structure adjacent to the right sternum and the diseases in the thoracic cavity and mediastinal diseases, and the common diseases are the lesion of the chest wall tissue and structure, the right thoracic cavity diseases and the mediastinal diseases. 1. Lesions of chest wall tissues and structures (1) Functional lesions of right chest muscles: for example, right chest muscle strain can cause right sternal pain. (2) Chest wall neuritis: such as costochondritis, intercostal neuritis can invade the junction of costochondral and sternum and cause right-sided sternal pain. (3) Sternal lesions: such as sternal fracture, sternal metastatic tumor and other sternal lesions can cause right-sided sternal pain. (4) Breast disease: female breast hyperplasia, breast cancer, etc. can also cause right-sided sternal pain. (2) Right thoracic cavity diseases: pneumonia, lung cancer pleurisy can cause right-sided sternal pain due to the involvement of right subpleural pleura and connective tissue. 3. Mediastinal diseases: thymoma, mediastinal tumor, etc. may invade the right posterior sternal tissues and cause referred pain. It is recommended to go to the hospital as soon as possible for further diagnosis and treatment of right sternal pain.