Book excerpt: Cytokines are well characterized molecules that control the communication between cells. Their importance in immunology is very critical for the control of the quantity and of the quality of each specific response against foreign antigens (virus, bacteria, ...). When the cytokine network is mis-regulated disease can appear (autoimmunity, immunodeficiencies like in AIDS or cancer). This comprehensive treatment of this exciting area of molecular medicine presents an informative description of the major cytokines together with coverage of their role in the different parts of the immune system and of their implication in immunopathology, and will be of great interest to medical researchers and academics in the field. Industrial researchers with an interest in immunology will also find this book useful.