Abstract: OBJECTIVE To investigate oral absorption of asiatic acid loaded nanostructured lipid carriers (AA-NLC) in rats. METHODS Biliary drainage model was established in conscious rats and pre-column derivatization HPLC was used to determine the concentration of AA in bile after oral administration of AA-NLC and AA (the control group) to rats respectively at the dosage of 50 mg·kg^-1. The absorption of AA nanoparticles was evaluated by comparing the concentrations of drugs. RESULTS In vivo study showed that the C_max of AA-NLC group was 1.7 times of the control group. The T_max of AA-NLC group prolonged significantly(P<0.05) in biliary excretion and the elimination half-life T_1/2 was 2.7 times of the control group. And the AUC_{0→24 h} increased to 150% compared to the control group. CONCLUSION The new assessment method can evaluate oral absorption of AA-NLC preliminarily. Nanostructured lipid carriers can increase the oral bioavailability of AA in rats.