PURPOSE: The need for completion axillary lymph node dissection, even in early breast cancer patients with a positive sentinel lymph node, has been questioned. The purpose of this study was to determine the factors that predict the presence of metastasis in non-sentinel lymph nodes (NSLNs) when the sentinel lymph node (SLN) was positive. METHODS: Between December 1998 and June 2004, the records of 104 early breast cancer patients with a positive SLN and who underwent completion axillary lymph node dissection were reviewed. The clinicopathological features in SLN-positive patients were evaluated as possible predictors of metastatic NSLN. RESULTS: Forty four (42.3%) of the 104 patients with positive SLN had metastatic NSLNs. In a univariate analysis, unicentric multifocality (P=0.016), lymphovascular invasion (P=0.006) and SLN metastasis larger than 2 mm (P= 0.003) were associated with positive NSLN findings. The number of SLNs removed was significantly associated as a negative predictor (P=0.043). A multivariate analysis revealed that SLN metastasis >2 mm (P=0.021) and lymphovascular invasion (P=0.040) were independent predictors of metastatic NSLN. CONCLUSION: The likelihood of metastatic NSLNs correlates with the size of the largest SLN metastasis and the presence of lymphovascular invasion of the primary tumor. Even though in early breast cancer with positive SLNs, incorporating these factors may help determining which patients would benefit from additional axillary lymph node dissection.