['Fifty percent of patients with sentinel lymph node (SLN) metastases have no metastatic disease in non-SLNs on axillary lymph node dissection (ALND). The goal of this study is to determine which patients have metastatic disease limited to the SLN, and, therefore, may not require completion ALND.', 'Of the first 1000 patients undergoing SLN biopsy at Memorial Sloan-Kettering Cancer Center, using a combined blue dye and isotope technique, 231 (26%) had positive SLN. Of these, 206 underwent completion ALND. They are the study group for this report.', 'The likelihood of non-SLN metastasis was inversely related to three clinicopathologic variables: tumor size < or = 1.0 cm; absence of lymphovascular invasion (LVI); and SLN micrometastases (< or = 2 mm). None of 24 patients with all three predictive factors had non-SLN metastases, whereas 58% of patients with none of the factors had disease in the non-SLN.'] Does lymphovascular invasion enhance the prediction of non-sentinel node metastases in breast cancer patients with positive sentinel nodes?