The aim of the study was to assess the value of a sentinel node biopsy with the use of a blue-dye-only technique as a tool for ultrastaging breast cancer in patients undergoing axillary lymphadenectomy. In order to maximize the efficacy of the method, we used a specific technique identifying blue-dyed lymph vessels during surgery. We took advantage of the wide surgical access to axillary lymph nodes.Material and methods. A blue dye technique for sentinel node biopsy was used during a modified radical mastectomy (Madden type) in 34 patients (85%) or during breast-conserving surgery with complete axillary dissection in six patients (15%).Results. The sentinel node(s) was identified in 39 of the 40 patients (97.5%). Metastases were detected in sentinel nodes in 14 out of these 39 patients. In one patient (1/39; 2.5%), micrometastasis was identified. The false-negative rate was 0%, sensitivity 100%, and negative-predictive value 100%.Conclusions. The blue dye method for sentinel node biopsy with wide access to the axilla is an effective and reliable tool for the identification of the sentinel node. The use of this simple technique permits ultrastaging of breast cancer patients undergoing complete axillary dissection.