BACKGROUND: Sentinel lymph node (SLN) mapping is the standard method for axillary lymph node staging in patients with breast cancer. Blue dye and radioisotopes are commonly used agents to localize SLNs, but both have several disadvantages. The purpose of this study was to evaluate magnetic resonance lymphography with a gadolinium-based contrast agent (Gd-MRL) in sentinel lymph node identification and metastasis detection in patients with breast cancer. METHODS: Sixty patients (mean age: 46.2 ± 8.8 years) with stage T1- 2 breast cancer and clinically negative axillary lymph nodes participated in this study. After 0.9 ml of contrast material and 0.1 ml of mepivacaine hydrochloride 1% were mixed and injected intradermally into the upper-outer periareolar areas, axillary lymph flow was tracked and sentinel lymph nodes were identified by Gd-MRL. After SLN biopsy and/or surgery, the efficacy of SLN identification and metastasis detection of Gd-MRL were examined. RESULTS: Ninety-six lymph nodes were identified by Gd-MRL as SLNs (M-SLN), and 135 lymph nodes were detected by blue dye-guided methods as SLNs (D-SLN). There was a strong correlation (P < 0.001) between the SLN numbers found by these two methods. Using blue dye-guided methods as the gold standard, the sensitivity of Gd-MRL was 95.65% and the false-negative rate was 4.3% for axillary lymphatic metastasis detection. With heterogeneous enhancement and enhancement defect as the diagnostic criteria, Gd-MRL gave a sensitivity of 89.29% and specificity of 89.66% in discriminating malignant from benign SLNs. CONCLUSION: Gd-MRL offers a new method for SLN identification and metastasis detection in patients with breast cancer.