Background:Cancer breast is a leading cause of death and the most common cancer in women. Early and accurate diagnosis remains a challenge. If breast cancer is found early, prompt treatment could save life.PET is a useful test for staging or re-staging breast cancer because its higher accuracy for finding local or distant disease. PET is sensitive in detection of clusters of tumor cells that have taken hold in other tissues or organs in the body. Aim of the study: The aim of the present study is to evaluate role of FDG PET/CT in diagnosis &staging of breast cancer. Patients and methods:This study was conducted on female patients known to have malignant breast lesion /lesions who were referred to radio-diagnosis & oncology departments. The present study demonstrated in correlation with other studies that PET/CT is sensitive in detection the primary breast masses but till now not the modality of choice in breast cancer diagnosis as PET/CT has important limitation such as high cost , significant radiation exposure and inability to detect small sized primary tumors. Results: The overall sensitivity of PET/CT in diagnosis &staging of breast was about 97%. Conclusion: The present study demonstrated in correlation with other studies that PET/CT is sensitive in detection the primary breast masses but till now not the modality of choice in breast cancer diagnosis as PET/CT has important limitation such as high cost , significant radiation exposure and inability to detect small sized primary tumors.