Modified radical mastectomy (MRM) results in postoperative acute pain ranging from mild to severe. This work aimed to assess the analgesic efficacy of transversus thoracic muscle plane-pectoral nerve (TTP-PECS) blocks after MRM. Methods: This pilot study was conducted on 10 females between the ages of 21 and 60 who were categorized as physical status II and III by the American Society of Anaesthesiologists (ASA) and underwent MRM under general anesthesia. TTP-PECS blocks were administered 30 minutes before the surgical incision using ultrasound guidance. Results: 3 (30%) patients needed intraoperative fentanyl. The mean (±SD) value of time to first request of rescue analgesia was 3.1 (± 0.88) h. The mean (±SD) value of the total amount of rescue morphine use was 30 (± 4.71) mg. The median (IQR) of visual analog scale was 1(0 - 1) at PACU, 1(1 - 1) at 1 h, 2.5(1.25 - 5.25) at 2h, 3(3 - 6.75) at 4 h, 3.5(3 - 6.25) at 6 h, 4(4 - 4.75) at 12 h and 4(3.25 - 4.75) at 24 h. Vascular injury, pneumothorax, local anesthetics (LA) toxicity, and anaphylactic shock didn’t occur in any patient. 2 (20%) patients suffered from postoperative nausea and vomiting (PONV). Ramsay sedation score was 2 in 7 (70%) patients, 3 in 2 (20%) patients, and 4 in 1 (10%) patient. Conclusions: In patients who underwent MRM, combination of TTP-PECS provided intraoperative and postoperative analgesic control and reduced morphine use.