A simple and rapid reversed-phase HPLC-UV method was developed for the determination of triterpenic acids in the crude extract of Prunellae Spica. Five triterpenic acids were extracted and isolated from P. Spica as marker compounds for use in the quality control of herbal medicines. Various solvent extraction techniques were evaluated, and the greatest efficiency was observed with sonication in 100% ethanol. Elemental compositions of the five marker compounds were determined by high-resolution mass spectroscopy. The dynamic range of the HPLC-UV method depended on the specific analyte, and acceptable quantitation was obtained between 10 and 250 microgmL(-1) for oleanolic acid, between 10 and 300 microgmL(-1) for ursolic acid, between 3 and 75 microgmL(-1) for 2alpha,3alpha,24-trihydroxyolean-12en-28oic acid, between 5 and 100 microgmL(-1) for euscaphic acid, and between 5 and 100 microgmL(-1) for 2alpha,3alpha-dihydroxyurs-12en-28oic acid. The method was deemed satisfactory by inter- and intra-day validation and exhibited both high accuracy and precision (relative standard deviation <9.4%). Overall limits of quantitation and detection were approximately 0.5-2.5 microgmL(-1) at a signal-to-noise ratio (S/N) of 3 and were about 3.0-10.0 microgmL(-1) at a S/N of 10. In addition, principal component analysis (PCA) was performed on the analytical data of 15 different P. Spica samples in order to classify samples collected from different regions.