This paper describes a validated high-performance liquid chromatographic method to quantitate four tanshinones as markers; dihydrotanshinone I, cryptotanshinone, tanshinone I and tanshinone IIA for use in the quality control of the roots of Salvia miltiorrhiza and its related traditional Chinese medicinal preparations. Separation was achieved using a Zorbax Extend C18 reserved-phase column (5microm, 250*4.6mm) at 20 degrees with a gradient mixture of deionized water and acetonitrile at a flow rate of 1.2ml/min. The limits of quantitation were 0.13, 0.08, 0.06 and 0.05microg/ml for dihydrotanshinone I, cryptotanshinone, tanshinone I and tanshinone IIA, respectively. This method provided good reproducibility and sensitivity for the quantification of four tanshinones with overall RSD values for intra-day and inter-day precision and accuracy better than 3.8% and higher than 94.9%, respectively. The recovery of the method was 95.4-104.4% for all the tanshinones and showed good linearity (r>0.9998) over a relatively wide concentration range. This assay was successfully applied to the determination of four tanshinones in the roots of Salvia miltiorrhiza and its related traditional Chinese medicinal preparations. The results indicated that the HPLC assay could be readily utilized as a quality control method for the roots of Salvia miltiorrhiza and its related traditional Chinese medicinal preparations.