The three dihydronaphtho[1,2,4]trioxines 9–11 have been synthesized and two of them converted to the five carbamate and ester derivatives 12–16 (Schemes 1 and 2). The resulting new trioxanes together with two already known and ascaridole (7) were tested for antimalarial activity against the sensitive N strain of Plasmodium berghei in mice. On comparison with artemisinin (1) and dihydroartemisinin (2), modest activity was found. The four most active compounds were some 12–18 times less potent than 1.