Cachexia consists of a constellation of metabolic changes that occur in cancer patients, including the reduction of muscle and fat tissue, asthenia, anorexia, hypoglycemia and hypercalcemia. These syndromes complicate therapeutic intervention and decrease the quality of life of the patient. This review discusses the involvement of cytokines in cancer cachexia and describes the contribution of IL-6 and other cytokines to the wasting of C-26-bearing mice. The neutralization of IL-6 by antibody, or IL-6 receptor antagonism by suramin, significantly reduce the severity of key parameters of cachexia. The participation of several other factors (PGE2, IL-1, IL-10 and TNF-alpha) in the cellular communication between the C-26 tumor cell and tumor-infiltrating macrophages is also described.