The method of sentinel lymphnode is a new procedure, suitable for the cases of early diagnosed breast cancers: identifying the first lymphatic station of the cancer, it can avoid the axillary lymphadenectomy in those women with primitive invasive and unifocal neoplasis of not more than 1.5 cm in diameter and without lymphnodal invasion. So it is reduced the frequency of postoperative troubles (sensitive and motor diseases, lymphedema). In our study, we have researched and identified, using radioactive isotopes, the sentinel lymphnode in 20 women suffering from subclinic breast cancer. We have obtained a percentage of 5% of false negatives. The optimal level of identification of the sentinel lymphnode and the good level of predictivity about the axillary lymphatic status, that we have obtained, represent a further confirmation of the surety and validity of this method.