A series of artemisinin (qinghaosu)-related trioxanes has been prepared and assayed in vitro for anti-HIV activity. One of these compounds, 12-n-butyldeoxoartemisinin shows a good antiviral activity against HIV-l.Artemisinin (Qinghaosu), 5, isolated from Artemisia annua, L., is a sesquiterpene lactone bearing an unusual cyclic peroxide function'. This natural product is of special interest because of its outstanding anti-malarial activitysa, in vitro activity against Pneumocystis carin@b and novel structuresal C-d. Unique endoperoxide within the molecule has prompted us to prepare artemisininrelated trioxanes and evaluate their in vitro anti-HIV activity. In this communication, we would like to report, for the first time, the structure-activity relationship of artemisinin derivatives.