Abstract: The prognosis and need or not for adjuvant therapy in patients with small breast tumors (≤1 cm N0) is the subject of controversy as regards the clinical benefit obtained, toxicity, and the economical costs generated. A retrospective analysis was made of 238 patients with early-stage breast cancer (pT1 ≤ 1 cm N0M0) diagnosed between January 1993 and May 2008. As regards the systemic adjuvant treatments provided, (a) 122 (51%) received no treatment, (b) 102 (43%) received hormone therapy, (c) 9 (4%) chemotherapy, and (d) 5 (2%) received both hormone therapy and chemotherapy. An analysis was made of disease-free survival (DFS) and breast cancer-specific survival in our series of patients, and of their correlation to clinicopathological factors (age, tumor size, histological grade, estrogen receptor (ER) expression, HER-2 overexpression, and systemic adjuvant therapy). The median follow-up of this cohort was 63 months (range 5–145). Some type of relapse was recorded in 4.2% of the patients (six patients presented local recurrence in all cases subjected to rescue treatment with surgery and/or radiotherapy, three patients developed distant metastases, and one patient presented a resected local recurrence followed by systemic relapse). The 5 year DFS was 96%, and the 5 year breast cancer-specific survival was 99.6%. A univariate analysis was made of the clinicopathological variables and their association to DFS. None of the variables was seen to be significantly correlated to shorter DSF except for an association between HER-2 overexpression and poor outcome borderline significance (p = 0.07). The prognosis of our pT1 ≤ 1 cm N0M0 tumors was excellent, although the absence of systemic adjuvant therapy in one-half of the patients.