Before planning therapeutic strategies for patients at different risks of relapse, it is essential to identify prognostic factors. In addition to important anatomo-pathological prognostic factors such as lymph node status and tumour size, certain biological indicators, such as receptor status and proliferative kinetics, are now regarded as useful tools for prognosis. Tumour cell kinetics is an important prognostic variable in different stages of breast cancer. It is also a useful index for identifying subjects of aggressive tumours in node-negative patients. As far as the relationship between TLI estrogen receptor status and tumor size is concerned, it has been observed that only TLI retains its prognostic significance as regards both time to relapse and overall survival. Lymph node status, receptor status, cell kinetics and c-erbB-2 expression were examined as predictive factors of response. It emerged that not all chemotherapeutic regimens have the same impact in a situation where the disease is evaluated exclusively on the basis of lymph node status. Moreover, receptor status and receptor level significantly condition the response to endocrine therapy. Response rates to chemotherapy increase in highly proliferating tumours, whereas endocrine therapy achieves a better response in ER+ tumours with a low TLI index. Further studies are needed to clarify the role of c-erbB-2 as a predictive factor of response.