There are several possible causes of left posterior rib pain: first, intercostal neuralgia, when there is chronic inflammation of the intercostal nerve or compression fracture or tumor compression, there can be intercostal nerve pain, which should be investigated, often as stabbing pain, hidden pain or radioactive pain, and if necessary, the relevant spinal MRI for diagnosis. Second, herpes zoster, in the early stages of herpes zoster can also appear in the left posterior rib pain, and after 1-2 weeks of incubation period there can often be clusters of herpes, which should be seen and treated in the dermatology department. Third, lung diseases, when there is a tumor in the lung or a tumor in the pleura, there can also be pain in the left posterior ribs. Fourth, diseases of the ribs, when there is a tumor or metastasis in the ribs, the left back rib pain can also appear.