PURPOSE: Although screening MMG leads to increase of early small breast cancer, axillary lymph node metastasis is still an important prognsotic factor in these patients. The aim of this study is to evaluate the incidence and predictors for axillary lymph node metastasis in patients with invasive breast carcinoma of 1 cm or less. METHODS: A retrospective analysis was made of 144 patients who underwent resection of primary tumor and axillary procedures between January 1999 and August 2009 for breast cancer of 1 cm or less in size. Patients were divided into two groups according to axillary node metastasis and clinicopathologic factors including age, palpable mass during physical examination, location of tumor, multifocality, tumor size, histologic type, extensive in situ component, histologic grade, nuclear grade, lymphovascular invasion, hormonal receptor status, and C-erbB-2 status were compared. RESULTS: Twenty-eight (19.4%) patients of all 144 patients had metastasis in the axillary lymph node. Three variables such as multifocality (P=0.023), histologic high grade (P=0.033), presence of lymphovascular invasion (P=0.002) were found to be significant in univariate analysis. In a multivariate logistic regression analysis, however, multifocality (P=0.022) and presence of lymphovascular invasion (P=0.007) were independent predictors of axillary lymph node metastasis. CONCLUSION: The incidence of axillary lymphnode metastasis of breast cancer 1 cm or less in size was 19.4%. Although the size of invasive breast carcinoma is less than 1 cm, if the tumor presented lymphovascular invasion or multifocality, axillary lymph node dissection might prove better than sentinel node biopsy.