Post-mastectomy pain syndrome (PMPS) can have multiple pain generators, including neuropathic pain and myofascial pain syndrome (MPS). Erector spinae plane (ESP) block and rhomboid intercostal block (RIB) have been used to provide anesthesia of the thorax and also for some chronic pain conditions. We describe a 43-year-old man suffering from right PMPS after right mastectomy, full axillary, and mammary lymph node dissection. We treated her with ESP blocks and RIB to reduce neuralgia and MPS: Neuropathic pain disappeared and the patient experienced only slight residual pain. The result was maintained 3 months later. This report suggests that ESP block and RIB with local anesthetic and corticosteroids with might be useful to treat a PMPS.