Axillary lymph node dissection (ALND) is recommended for patients with breast cancer metastasis to a sentinel lymph node (SLN). However in 40-70% of cases, the SLN may be the only area of metastasis in the dissected axillary contents. In patients with a positive SLN, independently predictive factors for non-SLN metastasis include size of the primary tumor, the size of the SLN metastases, extracapsular extension, and the proportion of positive SLN's among all identified SLNs. Some authors have developed scores and nomograms to estimate a patient's risk for non-SLN metastases. These scores and nomograms should be applied prospectively to a large numper of SLN positive patients who thereafter undergo completion ALND. It is necessary to verify the predictive validity of these scores before we recommend the abandonment of ALND in patients with a very low likelihood of non-SLN metastasis. In this article we review the various predictive factors of non-SLN involvement and the scores or nomograms which have been developed to predict the likelihood of a positive ALND after a positive SLN biopsy.