Adequate pain management following modified radical mastectomy (MRM) is crucial for early ambulation and patient satisfaction. Breast cancer is the most common malignancy in females, with an increasing incidence in recent years. Surgery is one of the mainstays of therapy for breast cancer, and modified radical mastectomy (MRM) is the most effective and common type of invasive surgical treatment. Post-mastectomy pain syndrome (PMPS) is a surgical complication of breast surgery characterized by chronic neuropathic pain. The aim of this study is to investigate the efficacy and safety of single injection CTB versus SAPB on post-operative acute pain as a part of a multimodal analgesia plan in patients undergoing MRM.