Abstract: A method is proposed for the determination of anthraquinone derivatives in whole blood, plasma, urine, faeces and various organs or tissues. The anthraquinone derivatives in the sample is first extracted with alcohol-ether mixture and hydrolysed with acid. The free anthraquinone derivatives are then extracted successively with chloroform and alkalie. The alkaline solution is acidified and again extracted with chloroform. Evaporate the chloroform to dryness. Dissolve the residue with methyl alcohol. Add Mgacetate reagent to give a pink colour which is determined colorimetrically. The recovery of this method is practically complete. The anthraquinone derivatives are equally distributed between the plasma and red cells.