Objective To explore the effect of carbon nanoparticles dyeing on axillary lymph node dissection in modified radical mastectomy for breast cancer. Methods Eighty-eight patients with breast cancer who received modified radical mastectomy in Mianyang Central Hospital between Mar. 2012 and May. 2013 were recruited in the study, and they were equally divided into areola group and peripheral tumor group. After induction of anesthesia before operation, carbon nanoparticles were injected around the areolar in the areola group, and carbon nanoparticles were injected around the tumor in the peripheral tumor group. The number of dissected lymph nodes(be dyed or not be dyed), metastatic lymph nodes, and black dyed lymph nodes, as well as value of operation related indexes were recorded and compared. Results In the areola group, lymph nodes were detected in 1 453, in which 1 396 lymph nodes were stained black(96.1%); the average number of dissected lymph nodes were 33.0±7.1 per case; and 19 patients (43.2%, in total of 220 metastatic lymph nodes) of them were suffered from lymph node metastasis with the average number of metastatic lymph nodes of 5±2 per case. in addition, in the areola group, operative time were(122.1±10.2) min, blood loss were(83.8±10.1) mL, postoperative hospital stay were(7±1) d, and postoperative complications occurred in 3 patients. In the peripheral tumor group, lymph nodes were detected in 909, in which 594 lymph nodes were stained black (65.3%); the average number of dissected lymph nodes were 20.7±3.2 per case; 20 patients (45.5%, in total of 88 metastatic lymph nodes) of them were suffered from lymph nodes metastasis, with the average number of metastatic lymph nodes of 2±1 per case. In addition, in the peripheral tumor group, operative time were (121.6±11.4) min, blood loss were (84.2±11.3) mL, postoperative hospital stay were (7±2) d, postoperative complications occurred in 3 patients. The black staining rate of lymph nodes, the number of lymph nodes retrieved, and the number of metastatic lymph nodes in areola group were significantly higher than those of peripheral tumor group(P < 0.01). Operative time, blood loss, postoperative hospital stay, and postoperative complication rate did not significantly differ between the 2 groups (P > 0.05). Conclusion The dyeing effect of carbon nanoparticles suspension, which was injected at areola area after induction of anesthesia, is better than that of injected around the tumor, without increasing the incidence of complication.