Orotidine 5′-monophosphate is a pyrimidine ribonucleoside and plays a role as an endogenous metabolite of human, E. coli or mouse. Orotidine 5′-monophosphate is an intermediate in the biosynthesis of uridine monophosphate (UMP). Orotidine 5′-monophosphate can be used for the study of mechanism of orotidine 5′-monophosphate decarboxylase.