Thirty-two patients affected by monolateral breast cancer and five patients with benign mammary pathology were submitted to pre-operative lymphoscintigraphy by sub-areolar injection of nanocolloidal albumin with the aim of evaluating any axillary lymphonodular involvement. The 32 patients, affected by cancer, subsequently underwent a surgical operation so as to permit a pathological-anatomical study of the axillary cavity. A comparison between the clinical and instrumental examinations brought to light the much greater reliability of the latter which gave 87.5% of correct diagnoses. The authors emphasize the absence of false positive results and the excellent sensitivity of the method in bringing to light even limited involvements of the axillary lymphonodes. The authors believe that axillary lymphoscintigraphy deserves to be included in the pre-operative protocols which afford a correct staging of the disease and, consequently, a better assessment of the extent of the surgical action.