Selective solvent extraction of anthraquinones (alizarin and lucidin) and their primeverosides (ruberythric acid and lucidin-3-o-primeveroside) from madder roots could be achieved using two-phase extraction with chloroform (CHCl3) and potassium hydroxide aqueous solution (KOHaq). Ruberythric acid extracted to the aqueous phase could be selectively and completely converted to alizarin within 360 min by enzymatic hydrolysis with beta-glucosidase at 50 degrees C and at pH 5, reducing the inhibitory effect on the reaction caused by alizarin, which is not extracted in appreciable amounts into the aqueous phase, without appreciable hydrolysis of lucidin-3-o-primeveroside. It was also found that ruberythric acid extracted from madder hairy roots by CHCl3-KOHaq two-phase extraction was efficiently converted to alizarin in the same manner.