Abstract: OBJECTIVE To investigate the absorption characteristics of asiatic acid(AA) in rats. METHODS In situ single pass perfusion mode was used and the HPLC method was established to explore the absorption kinetics of AA, the drug absorption was evaluated by effective permeability (P_eff), absorption rate constant (K_a) and fraction absorbed (f_a). RESULTS The calibration curve was found to be linear over the concentration range of 1.0~18.0 mg·mL^-1. With the increase of AA concentration, the accumulative absorption of AA was increased, and its absorption curve was shown to be linear. P_eff, K_a and f_a of AA at concentration of 30 mg·mL^-1 was (0.48±0.04)×10^-4·cm^-1·s^-1, (0.34±0.06)×10^-3·s^-1, (52.50±3.08)%, respectively. It was (0.55±0.14)×10^-4·cm^-1·s^-1, (0.34±0.05)× 10^-3·s^-1, (56.5±10.25)% at concentration of 9 mg·mL^-1, respectively. There was no significant difference of absorption parameters at concentration of 30 and 9 mg·mL^-1(P>0.05). The fa of AA at concentration of 30 mg·mL^-1 at duodenum, jejunum, ileum and colon was (59.59±13.08)%, (63.34±11.48)%, (66.95±8.01)%, (39.43±14.96)%, respectively. CONCLUSION AA can be classified into intermediate penetrating drug. It can be absorbed at all intestinal segments, and ileum was the best absorption segment. Its absorption is mainly via passive transport mechanism in intestine.