Abstract: A new method based on rat liver microsomes and chromatographic fingerprint comparison was established to investigate the possible herb-drug interactions between Liuwei Dihuang Pills(LDP)and nifedipine(NIF). LDP and NIF were incubated simultaneously with rat liver microsomes at 37 °C for 60 min in a shaking water bath. The separation was achieved on a C₁₈ column using 0. 1% formic acid solution and acetonitrile as mobile phase with a liner gradient program. The flow rate was set at 1. 0 mL/min. Detection was achieved by UV light at 240 nm. To evaluate the interactions between LDP and NIF, the similarity of the fingerprinting chromatograms before and after co-incubation was calculated by similarity evaluation system for chromatographic fingerprint of TCM. Furthermore, pharmacokinetic experiments in rat suggested that there was no significant difference in the pharmacokinetic parameters of the typical components in LDP.