1,4-Dihydroxyanthraquinone, also called quinizarin or Solvent Orange 86, is an organic compound derived from anthroquinone.

It is formally derived from anthraquinone by replacement of two hydrogen atoms by hydroxyl (OH) groups.

It is one of ten dihydroxyanthraquinone isomers and occurs in small amounts (as a glycoside) in the root of the madder plant, Rubia tinctorum.

[citation needed] Quinizarin is an inexpensive dye that is used to colour gasoline and some heating oils.

Amination (replacement of one OH by ArNH) with aniline derivatives followed by sulfonation affords other dyes such as Acid Violet 43.