The need for axillary lymph node dissection (ALND) in breast cancer patients with sentinel lymph node (SLN) micrometastases remains controversial. The aims of the study were to evaluate the locoregional failure and outcome of breast cancer patients with sentinel node micrometastases who did not undergo completion ALND. Between November 2000 and December 2006, SLN biopsy was successfully performed in 1178 patients with invasive breast carcinoma. Only patients with macrometastasis (>2 mm) underwent ALND, while patients with negative SLN or micrometastases did not undergo further treatment of the axilla, by either surgery or radiotherapy. Regarding adjuvant therapy decision, patients with SLN-micrometastases (pN1mi) were considered as node-positive patients. Of 1,178 patients, 59 (5%) had micrometastases. Of those with micrometastases, 14 (24%) underwent ALND because the intraoperative study of the SLN yielded a positive result. With a median follow-up of 60 (range, 8–94) months, none of the patients with SLN micrometastases in whom ALND was omitted developed an axillary recurrence, while one patient in whom ALND was performed developed infraclavicular lymph node recurrence. One patient, who declined postoperative breast irradiation, developed breast recurrence and distant metastasis. Breast cancer patients with SLN micrometastases in whom ALND was omitted had a very low locoregional failure rate. This study supports the theory that ALND might be avoided in these patients, providing that adjuvant systemic treatment equal to treatment provided to treat node-positive disease is administered. However, longer follow-up and results of additional prospective studies are needed.