The use of rodent tumor lines is no longer satisfactory for either biological and chemosensitivity studies because of their well demonstrated difference in behaviour when compared to human tumors. With the employment of human tumor cell lines, both in vitro and in vivo, in nude mice, it is now possible to utilize an extremely more reliable model system able to specifically evaluate many biological features of human tumors as well as their chemosensitivity. Particularly, glioma-derived human tumor lines which grow both in vitro and in nude mice, allowed to assess several parameters able to indicate new therapeutic strategies.