For context, it should be noted that breast cancer is by far the most common form of cancer in women. It accounts for approximately (38.8 percent) of all cancers that affect Egyptian women. Following any surgical procedure, postoperative discomfort is a major worry for patients. Pregnant women who have breast reconstruction surgery need a multimodal pain management strategy that is both effective and safe. A single injection or continuous infusion of a peripheral regional analgesic technique can provide analgesia superior to that provided by systemic opioids and may even lead to improvements across a number of outcomes. Local anaesthetic is injected between the deep fascial plane of the erector spinae muscle and the tip of the transverse process using ultrasound-guided erector spinae plane block (ESPB). Modified pectoral nerve block and erector spinae plane block are being compared for post-operative pain relief after modified radical mastectomy procedures. The study was conducted at Benha University Hospital using prospective, randomised, and double-blinded methods. Group (E) received 20 millilitres of 0.5 percent bupvicaine, while group (P) received 30 millilitres of 0.5 percent bupvicaine. The patients were divided equally between the two groups. Results: There was no statistically significant difference in the visual analogue scale between the two groups. Preoperative morphine consumption in the first 24 hours was not significantly different between the two groups, nor was the number of morphine increments. Both groups had similar levels of sensory block, ease of the technique, surgery time, anaesthesia time and adverse effects, with only a small difference in the onset and incidence of side effects. Mean arterial blood pressure and heart rate were found to be significantly different between the two groups of participants. In surgical procedures, various regional pain management techniques can be used. Intercostal nerve blocks in the pectoral muscles appear to block the anterior cutaneous medial branch, which results in better bilateral analgesia than the ESB and reduces the need for opioids. ESB, on the other hand, may be linked with larger hemodynamic alterations but less clinical importance because of its closeness to the intrathecal and epidural spaces