ObjectiveTo evaluate diagnostic value of 18F-FDG PET/CT for breast cancer and axillary lymph node metastases. MethodsLiterature search was conducted in PubMed (1966 to 2013.10, EMbase (1974 to 2013.10), The Cochrane Library (Issue 8, 2013), Web of Science (1950 to 2013.10), CBM (1978 to 2013.10), WanFang Data (1990 to 2013.10) and CNKI (1994 to 2013.10) to retrieve the diagnostic studies about PET/CT in the diagnosis of breast cancer and axillary lymph node metastasis. Two reviewers independently screened literature according to the inclusion and exclusion criteria, extracted data, and assessed methodological quality of included studies. Meta-analysis was then conducted using Meta-DiSc 1.4 software. ResultsA total of 25 studies involving 2 089 patients met the eligible criteria. With the comparison of pathological results used as the gold standard, pooled sensitivity (Sen) and specificity (Spe), pooled positive likelihood ratio (+LR), pooled negative likelihood ratio (-LR), pooled diagnostic odds ratio (DOR) and the area under (AUC) of the summary receiver-operating characteristic curve (SROC) were:a) for diagnosing breast cancer, 0.69 (95%CI 0.60 to 0.76), 0.98 (95%CI 0.94 to 1.00), 10.75 (95%CI 4.10 to 28.16), 0.16 (95%CI 0.02 to 1.13), 56.76 (95%CI 17.50 to 184.14), 0.962 6; and b) axillary lymph node metastases, 0.63 (95%CI 0.59 to 0.66), 0.92 (95%CI 0.91 to 0.94), 6.01 (95%CI 4.07 to 8.89), 0.39 (95%CI 0.30 to 0.50), 17.35 (95%CI 10.58 to 28.46), 0.866 4. Conclusion18F-FDG PET/CT has a middle-degree sensitivity and relatively good specificity in diagnosing breast cancer and axillary lymph node metastases which can be regarded as an effective and feasible method for preoperative staging of breast cancer.