This paper reports general and special to-xicological experiments on Qinghaosu and itsderivatives.Results point to the superiority ofQinghaosu and its derivatives over chloroquinein such respects as therapeutic index,marginof safety and side effects.It is pertinent there-fore to recommend these compounds for clinicaltrial as antimalarials.The main toxic effects of Qinghaosu weremanifested on the hemopoietic system,especial-ly the erythroid series,and the myocardium wassomewhat involved.These toxic reactions werehowever reversible.The teratogenicity experi-ments in mice and rats showed both Qinghaosuand artemether to be embryo-toxic,and clinicaltrials should take into account these toxic ef-fects.Further studies with various other animalspecies should be aimed at discovering whetherspecies differences exist.