The presence of immune infiltrates and specifically of memory T cells correlates with the clinical outcome in neoplastic diseases, demonstrating that tumors can be immunogenic and able to induce protective antitumor immune responses. On the other hand it is also getting clear that tumors may evade the immune system by several mechanisms, which ultimately and negatively affect tumor rejection. Goals of our studied are: first, to evaluate the characteristics of the spontaneous antitumor immune responses in neoplastic patients, to evaluate the impact that these immune responses have on the natural history of the neoplastic disease and to identify strategies for their implementation; second, to study mechanisms of immune evasion adopted by the tumors and to identify strategies to circumvent them. The information derived by those studies will help in the design of clinical protocols of immuno-biotherapy in neoplastic patients.