Abstract: This paper reports the fate of Artesunate studied by using GCMS, HPLC and TLCS methods.The result of experiments showed that Artesunate may be transformed in vivo in rats, rabbits and dogs into dihydroartemisinine which contains both epimers (α, RT=5.2 rain; β, RT=6.4 min). It has been shown that dihydroartemisinine is even more effective than Artesunate. Therefore, it can be considered as an active metabolite of Artesunate.The results showed a linear relationship between the logarithm of plasma dihydroartemisinine concentration versus time after i. v. administration of Artesunate in dogs. The pharmacokinetic parameters were as follows: T_1/2=10 min; V_d=0.36L/kg.Artesunate and artemisinine derivatives were shown to have inductive effect on hepatomicrosomal enzymes. It showed a very remarkble first pass effect.