Chloroquine and mefloquine are available for prophylactic treatment in malaria, against a background of the burgeoning problem of resistance developing to chloroquine and related drugs (Mehlhorn and Schrevel 1995). For this reason, highly specific national recommendations are given out regarding prophylaxis. The option of a viable vaccine is currently not available. More new compounds are therefore urgently required, since 2-5 million of the 200 300 million infected people die each year. At the moment, atovaquone and artemisinin derivatives are of great interest, as are drug combinations such as atovaquone/proguanil (since 1997), artemether/ benflumetol (since 1998?; Ciba-Geigy, patent WO9202217) and chlorproguanil/dapsone (since 2000?), as these compounds are also effective against multi-resistant strains of Plasmodium falciparum (Tables 1, 2; Croft 1997; Wang 1997). Pyronaridin (since 2000?) has been discovered in a Chinese academy and is in clinical trials (Trouiller and Olliaro 1998; Pecoul et al. 1999).