Abstract: Sentinel node (SN) biopsy in breast cancer patients following preoperative chemotherapy is associated with a decreased identification rate and an increased false-negative rate when compared to SN biopsy performed in untreated patients. We performed SN biopsy in 21 breast cancer patients scheduled for preoperative chemotherapy using either vital blue dye alone (n = 11) or in combination with a radiocolloid (n = 10). Following a mean of four cycles of preoperative chemotherapy, surgery to the breast and complete axillary lymph node dissection was performed irrespective of the SN status. A mean of 1.9 SNs were identified in all 21 patients, 12 were SN negative and 9 were SN positive. Preoperative chemotherapy decreased mean tumor size from 40.2 to 17.7 mm and breast conservation was possible in 14 of 21 patients (67%). All SN-negative patients and three of nine SN-positive patients had negative lymph nodes in the axillary specimen, whereas six of nine patients with a positive SN revealed lymph node metastases following preoperative chemotherapy. SN biopsy performed before preoperative chemotherapy found a 100% identification rate with no false-negative results. Following preoperative chemotherapy, SN-negative patients may forego a complete axillary dissection.