To evaluate retrospectively the accuracy of integrated PET/CT, against PET, CT, or conventional staging in breast cancer. Seventy consecutive biopsy proven clinical stage IIB and III breast cancer patients were included. Descriptive statistics of integrated PET/CT for the primary tumor, nodal status and metastasis detection were compared to PET, CT with contrast, and conventional staging (biochemistry, chest X-ray, liver ultrasound, and bone scintigraphy). Sensitivity of PET/CT for primary tumor and nodal status was 97.1% and 62.5%, respectively. Specificity and negative predictive value for nodal status were 100% and 66.6%, respectively. The values for conventional staging for nodal involvement were 100% and 85.7% with a sensitivity of 87.5%. PET/CT showed metastatic disease in seven women despite normal conventional staging. PET/CT is able to visualize most clinical stage IIB and III primary breast cancers. PET/CT is superior to conventional staging for detecting internal mammary chain nodes and metastatic disease, but not for axillary staging. Future studies will have to test whether therapy adjustment based on PET/CT has the potential to improve survival.