To study the relationship between the expressions of Ki-67, WT p53, Bcl-2 proteins and tumor grade, on fine needle aspiration biopsies (FNABs), in patients with invasive ductal breast carcinomas. One hundred (100) FNABs were performed from the same number of female patients, diagnosed cytologically and confirmed histologically after oncectomy. The same cases were studied immunocytochemically using the monoclonal antibodies Ki-67, WT p53 and Bcl-2 by the alkaline phosphatase (APAAP) method and correlated to the nuclear and histological grade of the tumors. An association and a relationship was found between the grade of the tumors and the immunoexpression of Ki-67, WT p53 and Bcl-2 proteins (p < 0.005). The relationship between Ki-67, WT p53 and Bcl-2 proteins and the grade of the invasive ductal breast carcinomas seems to be a significant prognostic factor and should be kept in mind in follow-up patients after previous treatment for breast cancer.