In early stages of breast cancer, breast conservation therapy (BCT) with lumpectomy and adjuvant irradiation is preferred. Accelerated partial breast irradiation (APBI) is considered as an alternative to whole breast irradiation. The reasons are it requires less number of irradiation fractions, shorter treatment time, and decreased size of irradiation. The procedure includes insertion of several brachycatheters, which is associated with significant pain in the postoperative period. We report case series of 8 patients of APBI where perioperative pain management was done using ultrasound (USG)-guided serratus anterior plane (SAP) block with catheter insertion. The catheter was placed between the serratus anterior muscle and external intercostal muscle. The drug used was 0.4 mL.kg-1 of 0.375% Ropivacaine with a maximum value of 30 mL. On the day of the procedure, all patients were given two boluses of ropivacaine 20 mL each at an interval of 6 h. From the next day onward, they received ropivacaine boluses on demand basis when Numerical Rating Scale (NRS) was >4. There were no complications during the procedure. None of the patients required extra fentanyl boluses intraoperatively. One patient did not have an SAP catheter inserted during primary insertion, as she failed to give consent for block. On repositioning of catheters, she experienced severe pain with a NRS of 8/10. After obtaining proper consent, SAP catheter was inserted and she had NRS of 1/10 postoperatively. 2/8 patients received rescue analgesics in the form of diclofenac. 7/8 SAP catheters were removed on day 5. Only one SAP catheter was removed accidentally on day 3. It was concluded that USG-guided SAP catheters are a novel, safe, and effective regional anesthesia technique for perioperative pain management in breast cancer surgeries undergoing APBI.