Autoimmune inflammatory responses and the diseases that develop as a consequence are now thought to be driven through a novel non-Th(1) pathway. IL-23, together with additional factors including TGF-beta1 and IL-6, collectively generate and sustain a distinct CD4(+) 'Th(17) inflammation effector' T-cell subset characterized by its production of inflammatory chemokines and cytokines, including IL-17. With this paradigm shift in understanding of autoimmune inflammation pathogenesis comes exciting opportunities to identify and to target therapeutically molecules within the IL-23/Th(17) axis that are key to disease development.