Hidden pain inside the ribs on the left lower side of the chest may be due to intercostal neuralgia, pleurisy, costochondritis and other diseases, etc. Patients should go to the orthopedic department of the hospital for examination and symptomatic treatment. 1. Intercostal neuralgia: Intercostal neuralgia is usually induced by spinal trauma and tuberculous factors. Intercostal neuralgia may also occur when there is thoracic spine trauma. If obvious intercostal neuralgia occurs, patients are advised to go to the hospital for active examination and treatment. When spinal tuberculosis occurs, the intercostal nerves may be involved. Intercostal neuralgia may also occur when there is trauma to the thoracic spine. 2. Pleurisy: A variety of factors may lead to pleurisy, which may be an inflammatory disease that occurs in the pleural tissue itself, or it may be a symptom caused by other diseases that invade the pleura. If the patient develops pleurisy, it can also cause corresponding pain in the ribs on the lower side of the left chest. 3. Costal chondritis: Costal chondritis is mainly caused by patient’s exertion, strain, trauma, or infection. Clinical manifestations of localized pain in the ribs, severe costochondritis will also affect the patient’s daily activities. Hidden pain inside the ribs on the lower side of the left chest needs to be clarified by the cardiothoracic surgery or orthopedic department of the hospital as soon as possible.