Background: The sentinel lymph node procedure is a widely accepted method for staging of patients with early breast cancer. This study evaluates the incidence of axillary relapse after negative sentinel node biopsy in the seven hospitals in the central part of the Netherlands. Methods: This study concerns all patients with a T1-2 breast carcinoma who were staged with a sentinel lymph node biopsy in one of the hospitals in the region. Patients with a tumour-free sentinel node without additional axillary lymph node dissection and patients with a sentinel node containing micrometastases were prospectively included and data concerning tumour and primary treatment were recorded. After a median follow-up period of 46 months supplementary data were collected of all patients. Results: Between January 2002 and December 2003, 541 patients underwent a sentinel node biopsy of which the sentinel node was negative for metastatic disease. During the follow-up period three patients were diagnosed with an axillary recurrence. The incidence of axillary relapse after tumour negative sentinel node biopsy in this study is 0.6% (3/541). In 23 patients a distant metastasis developed. An event occurred in 11% of the patients with a micrometastasis in the sentinel node. This was not significantly different from the patients with a tumour-free sentinel node. Conclusion: The results suggest that the sentinel lymph node procedure as performed in the region Middle Netherlands is a reliable and accurate instrument for staging of patients with early breast cancer. In our study we observed a non-significant different risk of distant disease in case of micrometastases compared to a tumour negative sentinel node.