Aim: To study pharmacokinetics of aconitine,mesaconitine and hypaconitine in rats after single oral administration of decoctions composed with Radix Aconiti Lateralis.Methods: Four groups of rats were orally administered four decoctions including decoction a(Sini decoction),decoction b(decoction composed with Radix Aconiti Lateralis),decoction c(decoction composed with Radix Aconiti Laterali and Radix et Rhizoma Glycyrrhizae Praeparata Cum Melle)and decoction d(decoction composed with Radix Aconiti Laterali and Rhizoma Zingiberis),respectively.Quantitative analysis of aconitine,mesaconitine and hypaconitine in rat plasma was achieved using a liquid chromatography-electrospray ionization/tandem mass spectrometry method.Pharmacokinetic parameters were estimated using DAS 2.0.Results: Pharmacokinetic parameters of aconitine,mesaconitine and hypaconitine were different after oral administration of four decoctions according to Radix Aconiti Laterali combined with different herbal medicines.Multiple peaks were observed in plasma concentration-time curve after oral administration of the decoction of herb couple Radix Aconiti Laterali and Radix et Rhizoma Glycyrrhizae Praeparata Cum Melle,and the results showed a delay in tmax and a prolonger in MRT0-t compared with the decoction of Radix Aconiti Latera-lis.When Radix Aconiti Lateralis was combined with Radix et Rhizoma Glycyrrhizae Praeparata Cum Melle and Rhizoma Zingiberis at the same time in Sini decoction,tmax was delayed too but MRT0-t,was shorten than that of the group of Radix Aconiti Lateralis.Conclusion: The pharmacokinetic parameters of the three compounds obtained in this work shows that the pharmacokinetics of aconitine,mesaconitine and hypaconitine were influenced diversely when Radix Aconiti Laterali was combined with different herbal medicines.