A method using a high-performance liquid chromatograph coupled with a photodiode array UV detector (HPLC-DAD) and an electrospray ionization mass spectrometer (HPLC-ESI/MS) was developed for the quality assessment (fingerprinting and simultaneous quantification of 10 major constituents) of Zuo Gui Wan (ZGW), a Traditional Chinese Medicine (TCM). The compounds were identified on the basis of comparison of their mass spectra with literature data and standard samples and quantified by the HPLC-DAD method. Baseline separation was achieved on an ODS-100V C(18) column (3.0 microm, 150 mm x 4.6 mm I.D.) with linear gradient elution of acetonitrile-0.1% formic acid. The method was validated for linearity (r(2)>0.9996), repeatability (R.S.D.<3.5%), intra- and inter-day precision (R.S.D.<2.0%) with accuracy (91.8-99.7%), recovery (99.9-105.6%), limits of detection (1.4-22.0 ng), and limits of quantification (3.4-73.4 ng). The 10 compounds were selected for quality assessment of ZGW by using partial least squares-discrimination analysis (PLS-DA). The similarities of 20 batches of ZGW and their classification according to their manufacturers were based on the retention times and peak areas of the characteristic compounds.