Background Prognosis and treatment options differ for each molecular subtype of breast cancer, but risk of regional lymph node (LN) metastasis for each subtype has not been well-studied. Since LN status is the most important predictor for prognosis, the aim of this study is to investigate the propensity for LN metastasis in each of the five breast cancer molecular subtypes. Methods Under an IRB-approved protocol, we retrospectively reviewed the charts of all pathologically confirmed breast cancer cases from 1/2004 to 6/2012. Five subtypes were defined as luminal A (hormone receptor +, Ki67 low), luminal B (hormone receptor+, Ki67 high), luminal-human epidermal growth factor receptor 2 (HER-2), HER-2-enriched (hormone receptor negative), and triple negative (TN). Results A total of 375 patients with complete data were classified by subtype: 95 (25.3%) luminal A, 120 (32%) luminal B, 69 (18.4%) luminal-HER-2, 26 (6.9%) HER-2-enriched, and 65 (17.3%) TN. On univariate analysis, age (<50), higher tumor grade, HER-2 + status, tumor size, and molecular subtype were significant for LN positivity. Molecular subtype correlated strongly with tumors size (X2; p=0.0004); therefore, multivariable logistic regression did not identify molecular subtype as an independent variable to predict LN positivity. Conclusions Luminal A tumors have the lowest risk of LN metastasis, while luminal HER-2 subtype has the highest risk of LN metastasis. Immunohistochemical-based molecular classification can be readily performed and knowledge of the factors that affect LN status may help with treatment decisions.