Xanthines and xanthine-like DPP-IV inhibitors were first disclosed in 2002. Since then, several dozen accounts of xanthine-based DPP-IV inhibitors have been published. Only a few presentations and journal articles have appeared, with the vast majority of information coming from the patent literature. DPP-IV inhibitors related to the xanthines include purine analogues with other arrangements of the nitrogen atoms in the core structure, imidazoles, uracils, pyrimidines, pyridines, and some fused pyridines. At least one compound derived from the xanthines has advanced into clinical trials, making it likely that these molecules will play a major role in the DPP-IV inhibition arena over the next several years.