Cytokines are a group of molecules with an extremely broad range of activities on a variety of target cells. This review summarizes the known cytokine and cytokine receptor expression in primary brain tumors and derived cell lines. These expression patterns are compared with those occurring in other CNS diseases, such as virus or bacterial infections, experimental allergic encephalitis, multiple sclerosis, and trauma. A variety of cytokines are expressed during CNS neoplasia; their potential involvement in tumor growth through a variety of mechanisms, such as autocrine or paracrine growth stimulation, angiogenesis, and immune surveillance evasion, are discussed. Finally, results of preliminary therapeutic approaches with cytokines are critically evaluated.