In enzymology, an ethanolamine-phosphate cytidylyltransferase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are CTP and ethanolamine phosphate, whereas its two products are diphosphate and CDP-ethanolamine.
This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing nucleotide groups (nucleotidyltransferases). The systematic name of this enzyme class is CTP:ethanolamine-phosphate cytidylyltransferase. Other names in common use include phosphorylethanolamine transferase, ET, CTP-phosphoethanolamine cytidylyltransferase, phosphoethanolamine cytidylyltransferase, and ethanolamine phosphate cytidylyltransferase. This enzyme participates in aminophosphonate metabolism and glycerophospholipid metabolism.