Background: Breast Cancer (BC) in Argentina (A) is the most common cancer among women and the first cause of death by cancer (5,261 deaths in 2008, 6.98% in women under 44 years). Tucumán (T) has a predominantly urban population (79.46%), Census 2010, INDEC. BC mortality is 18.6/ 100,000 women (MSP, 2007) which means about 140 BC deaths /year and age-adjusted incidence 1994-96: 83/100 000/year (Herrera, Zarba et al). In 2008, 138 patients (pts) were diagnosed with BC in the public health subsector in T (PPCCMT). Women in T have an oncologic profile similar to those in developed countries. Pts under 45 with BC, have worse prognosis, an increased chance of dying from BC (5% yearly prior these age) and a significant reduction on life expectancy (Vinh-Hung et al, 2004). The young age of a patient is an independent indicator of poor survival. Objective: To analyze clinical-pathological features in pts with BC, diagnosed outside the range of screening in PPCCMT (< 40 years old). Methods: The features of 1016 pts with BC were studied reviewing the records of 4 diagnostic nodes, from January 2004 to July 2009. Pts with an age equal to or less than 39 years were selected. The variables studied included: age, tumor size, histological type and grade of the invasive carcinoma. An observational descriptive statistical method was applied. Results: We found reports of 84 (8,27%) pts with BC under 39 years old. Mean age: 34 years old (15 - 39). Median age: 35 years old. Invasive Ductal Carcinoma (IDC) was the most frequent histological type 58/84 (69%). Age frequency: <19: 1(1%); 20-24: 3 (4%); 25-29: 11 (13%); 30-34: 24 (29%); 35-39:45 (53%). Histological type: IDC: 41 (50%); IDC + DCIS:17 (20%); DCIS: 6 (7%); Invasive lobular carcinoma + LCIS: 6 (7%); Mixed: 3 (4%); Phyllodes: 4 (5%); Others: 5 (6.%). Size tumor: T1a: 2%; T1b:1%; T1c:11%; T2: 26%; T3:18% Unavailable (Core biopsies): 17%, Unregistered:25%. Histological Grade (Nottingham Score) Grade 1:5%, Grade 2:35%, Grade 3:17%, Unavailable: 43%. Conclusions: Our results showed a higher frequency of BC among women under 40 years old (8,27%) than in USA (7%). Diagnosing breast cancer in younger women is more difficult and it’s a challenge for the future. We must be careful with the “wait and see” concept in a young woman with a breast lump.