Background: In cancer, positron emission tomography (PET) using 18 fluorine (18f) fluorodeoxyglucose (FDG) plays an essential role. Its function in breast cancer management is evolving. In most nuclear medicine departments, combined PET and computed tomography (CT) equipment have superseded PET alone in recent years. Aim: To assess the added value of PET/CT scan in evaluation of pathological response to neoadjuvant chemotherapy in locally advanced or metastatic breast cancer patients before surgery. Subjects and methods: This study was conducted on forty-four female patients with evidence of proven breast cancer who were referred to PET/CT Unit at Department of Nuclear Medicine in International Medical Center. All clinical and histopathological data were extracted from the patients' clinical sheet. This included the pathological data and the current indication for FDG-PET/CT referral. All patients had a pretreatment PET/CT examination and post chemotherapy PET/CT follow up examination. Results: 27 patients (61.3%) showed response after non-adjuvant chemotherapy by pathology. Regarding SUV max, 31 patients (70.4%) showed response (where 6.8% of them revealed complete response and 63.6% revealed partial response). PET CT SUV max revealed that 31 patients as responders and 13 patients as non-responders. Among 31 responders, 27 were TP, 4 were FP. Among 13 non-responders, 13 were TN. The sensitivity, specificity and accuracy were 100%, 76.5% and 90.9% respectively. Conclusion: PET/CT is a reliable whole body single imaging which can be used in monitoring and evaluation of NAC response in breast cancer patients showing response, high sensitivity, and accuracy compared to CT alone.