It was reported in our previous work that some oarbogyho esters and carbonates of dihydroarteannuin (dihydroartemisinine)^* were highly potent antimalarial agents. In the course of the preparation of more derivatives, we met difficulty in aoylation by means of acid anliydride or acid chloride with pyridine or by means of oarbogylio acid with DCCS. We therefore employed 4-(N, N-dimethylamino)pyridine (DMAP) as catalyst for the aoylation of dihydroarteannuin. It was successful in the preparation of many esters. It is the first case to use DMAP in the aoylation of laotol. Many of the compounds prepared were found to be more than ten times as active as arteannuin against Plasmodvum berglzei in mine.