Abstract: The study aims to investigate different pharmacokinetic profilesof anthraquinones after oral administration of Rhei Radix et Rhizoma and Niuhuang Jiedu Tablets(NHJDT)in rats, respectively. Rats were administrated with 96 mg/kg of Rhei Radix et Rhizoma(1. 83 mg/kg of total anthraquinone, equivalent to 0. 28 mg/kg of rhein, 0. 30 mg/kg of emodin, 0. 81 mg/kg of chrysophanol, 0. 23 mg/kg of aloe-emodin and 0. 20 mg/kg of physcion)or 250 mg/kg of NHJDT(equal dose of total anthraquinone as Rhei Radix et Rhizoma, equivalent to 0. 33 mg/kg of rhein, 0. 38 mg/kg of emodin, 0. 71 mg/kg of chrysophanol, 0. 24 mg/kg of aloe-emodin and 0. 17 mg/kg of physcion), respectively. Followed by protein precipitation with methanol, the anthraquinones in plasma samples were determined by LC-MS/MS. The pharmacokinetic parameters were calculated by WinNonlin 7. 0. The c_maxof rhein were(121±103)and(474±251)μg/L, and the AUC0-twere(275±176)and(406±194)μg ·h/L for Rhei Radix et Rhizoma and NHJDT, respectively. The c_maxof chrysophanol isomer were(2 325±1 390)and(3 580±2 169)μg/L, and the AUC0-twere(8 170±2 661)and(8 856±4 023)μg ·h/L, respectively. Emodin in very low levels was only detected in rat plasma samples after oral gavage of NHJDT. The c_max, AUC and t1/2 of rhein, as well as Vd and CL of chrysophanol isomer were observed with a much increased degree in comparison with Rhei Radix et Rhizoma counterparts. However, much shorter t_maxwas found in NHJDT group. Therefore, NHJDT with co-existing components enhanced the absorption and influenced the pharmacokinetic behaviors of active ingredients in Rhei Radix et Rhizoma.