The study is designed as a prospective, double-blinded, randomize controlled study. The patients who will undergo mastectomy surgery with or without axillary dissection will be included in the study. Anesthesia will be inducted with intravenous (iv) thiopental 5 mg/kg, fentanyl 2 mcg/kg and rocuronium bromide 0.6 mg/kg. Following intubation, patients will be allocated into two groups according to a randomization table created by a professional statistician. In the study group, patients will receive a single shot Rhomboid Intercostal Block (RIB) with 30 milliliters of %0.25 bupivacaine and in the control group no block procedure will be performed. All patients will receive a standard analgesia protocol which will include an intraoperative intravenous (iv) infusion of dexketoprofen 50 mg and iv tramadol 1 mg/kg 15 minutes prior to the end of the surgery. Postoperative pain intensity of the patients will be evaluated by Numerical Rating Scale (NRS) which is a scale ranges between 0 (no pain) and 10 (the worst pain that a person can stand). Pain scores of the patients will be recorded at the postoperative 15. and 30. min in the recovery room and if the NRS score is 4 or more, iv fentanyl 1 mcg/kg will be applied. At the surgical ward, pain scores will be evaluated at the postoperative 1st, 2nd, 6th, 12th and 24th hours and if the NRS score is 4 or more, iv tramadol 50 mg will be applied as rescue analgesia. Opioid consumptions of the patients will be recorded at the postoperative 24th hour. At the postoperative 3. and 6. months, a pain doctor will evaluate all patients by using Brief Pain Inventory Short Form (BPI-SF) and Douleur Neuropathique 4 (DN4) questionnaire.