The Pectoralis II (PECS II) block is an interfascial block that surgeons can perform independently under ultrasound for our partial mastectomy patients to reduce postoperative pain and mitigate narcotic use. PECS II block is divided into two blocks the Pectoralis I and the Pectoralis II block. The Pectoralis I block targets the area between pectoralis major and pectoralis minor with local anesthesia. The Pectoralis II block includes the Pectoralis I block and targets the area between pectoralis minor and serratus anterior. Patient is kept supine with ipsilateral arm of operative breast abducted. . A linear ultrasound probe of high frequency (6-13 MHz) of a portable ultrasound system is used with an imaging depth of 4 to 6 cm. The probe is placed on lateral third of clavicle and moved laterally to locate vessels directly above the 1^st rib. Axillary artery and vein are identified and subsequently avoided. After the probe is moved laterally and inferiorly to identify the 3^rd and 4^th ribs where relevant anatomical structures pectoralis major, pectoralis minor and serratus anterior are identified. 10 cc of 0.25% Marcaine is instilled between pectoralis major and pectoralis minor using a 20-gauge spinal needle. An additional 10 cc of 0.25% Marcaine is placed between serratus anterior and pectoralis minor. All patients that receive the PECS block also receive 10 cc of 0.25% Marcaine subcutaneously at incision sites. All patients are sent home on standing acetaminophen and ibuprofen for the first 72 hours.