We report our multicentric experience with sentinel lymph node biopsy for breast cancer patients. Patients with breast cancer operated on from January 1999 to March 2005 in 6 different institutions in the Rome area were retrospectively reviewed. All patients gave written informed consent. 1440 consecutive patients were analysed, with a median age of 59 years (range: 33-81) and a median tumour diameter of 1.3 cm (range: 0.1-5). Patients underwent lymphatic mapping with Tc99 nanocolloid (N = 701; 49%), with Evans Blue (N = 70; 5%), or with a combined injection (N = 669, 46%). The majority of patients were mapped with an intradermal or subdermal injection (N = 1193; 84%), while an intraparenchymal or peritumoral injection was used in 41 (3%) and 206 patients (13%), respectively. Sentinel lymph nodes were identified in 1374/1440 cases (95.4%), and 2075 sentinel lymph nodes were analysed (average 1.5/patient). A total of 9305 additional non-sentinel lymph-nodes were removed (median 6/patient). Correlations between sentinel lymph nodes and final lymph node status were found in 1355/1374 cases (98.6%). There were 19 false-negative cases (5%). Lymph node metastases were diagnosed in 325 patients (24%). In this group, micrometastases (< 2 mm in diameter) were diagnosed in 103 cases (7.6%). Additionally, isolated tumour cells were reported in 61 patients (4,5%). In positive cases, additional metastases in non-sentinel lymph-nodes were identified in 117/325 cases after axillary dissection (36%). Axillary dissection was avoided in 745/1440 patients (52%). At a median follow-up of 36 months, only 1 axillary recurrence has been reported. Sentinel lymph node biopsy improves staging in women with breast cancer because it is accurate and reproducible, and allows detection of micrometastases and isolated tumour cells that would otherwise be missed. Our multicentric study confirms that this is the preferred axillary staging procedure in women with breast cancer.