Artemisia annua L. (annual wormwood) contains the antimalarial artemisinin. Aqueous preparations of the dried herb are included in the pharmacopoeia of the People's Republic of China for treatment of fever and malaria. Fourteen healthy male volunteers received one liter of tea prepared from nine grams of Artemisia annua leaves. Blood samples were taken and artemisinin was detected by reversed phase high-performance liquid chromatography. The mean +/- SD maximum plasma concentration of artemisinin was 240 +/- 75 ng/mL and the mean +/- SD area under the plasma concentration-time curve was 336 +/- 71 ng/mL x hr. Artemisinin was absorbed faster from herbal tea preparations than from oral solid dosage forms, but bioavailability was similar. One liter of an aqueous preparation of nine grams of Artemisia annua contained 94.5 milligrams of artemisinin (approximately 19% of the usually recommended daily dose). Artemisinin plasma concentrations after intake of this herbal tea are sufficient for clinical effects, but insufficient to recommend such preparations as equivalent substitutes for modern artemisinin drugs in malaria therapy.