thumb|right|100px|Pyrimidine
Pyrimidinediones are a class of chemical compounds characterized by a pyrimidine ring substituted with two carbonyl groups.
Examples include naturally occurring metabolites:
{| class="wikitable"
! Trivial name !! IUPAC name !! Structure!!Pathway
|-
|Uracil||Pyrimidine-2,4(1H,3H)-dione||Image:Uracil.svg||Pyrimidine biosynthesis
|-
|Thymine||5-Methylpyrimidine-2,4(1H,3H)-dione||150px||Pyrimidine biosynthesis
|-
| ||5,6-Diaminopyrimidine-2,4(1H,3H)-dione|| ||Riboflavin biosynthesis
|}
drugs:
thumb|right|Primidone
- Fluorouracil
- Idoxuridine
- Primidone
- Trifluridine
and pesticides:
- Bromacil
- Saflufenacil