Orotic acid is a heterocyclic compound and an acid; it is also known as pyrimidinecarboxylic acid. Historically it was believed to be part of the vitamin B complex and was called vitamin B₁₃, but it is now known that it is not a vitamin.

The compound is manufactured in the body via a mitochondrial enzyme, dihydroorotate dehydrogenase. or a cytoplasmic enzyme of pyrimidine synthesis pathway. It is sometimes used as a mineral carrier in some dietary supplements (to increase their bioavailability), most commonly for lithium orotate.