Uridine monophosphate a nucleotide that is found in RNA. It is an ester of phosphoric acid with the nucleoside uridine. UMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase uracil; hence, it is a ribonucleoside monophosphate. Another common shorthand for the molecule is uridylate - the deprotonated form of the molecule, which is predominant in aqueous solution. As a substituent it takes the form of the prefix uridylyl-.

Uridine monophosphate is formed from orotidylic acid (orotidine 5'-monophosphate) in a decarboxylation reaction catalyzed by the enzyme orotidylate decarboxylase. Uncatalyzed, the decarboxylation reaction is extremely slow (estimated to occur on average one time per 78 million years). Adequately catalyzed, the reaction takes place once per second, an increase of 10¹⁷-fold.