OBJECTIVE : The prognostic value of nonsentinel lymph-node (NSLN) status in breast cancer remains unclear. This study was designed to investigate the prognostic value of NSLN status in SLN-positive breast cancer. METHODS : Retrospective 873 consecutive primary breast cancer patients from a single institution who were SLN-positive and underwent axillary lymph-node dissection (ALND) were included. Patients with incomplete clinical information or loss of follow-up were excluded. Survival analysis in patients with the same number of positive LNs and patients belonging to the same American Joint Committee on Cancer (AJCC) node (N) classification was performed to establish a proposal for incorporating the NSLN status into the breast cancer staging system. RESULTS : The median follow-up was 41 months. Positive NSLN status was a significantly unfavorable factor for recurrence-free survival (RFS) (HR: 4.31, P < 0.001) and distant recurrence-free survival (DRFS) (HR: 3.62, P < 0.001). The survival of patients with one positive SLN and one positive NSLN (N = 97) was significantly worse than that of patients with two positive SLNs (N = 68; RFS, P = 0.011; DRFS, P = 0.027). Positive NSLN status was a significantly unfavorable factor affecting survival in patients with the AJCC N1 classification (N = 806; RFS, HR: 2.85, P = 0.002; DRFS, HR: 2.81, P = 0.004). No significant difference in survival was found between LN-negative (N = 361) and NSLN-negative AJCC N1 classification (N = 363) patients. CONCLUSIONS : Positive NSLN status has an independent prognostic value in breast cancer patients with 1-3 positive LNs, and the NSLN status should be incorporated into the breast cancer staging system.