High performance liquid chromatographic method with diode-array detection (HPLC-DAD) has been performed for the simultaneous determination of four marker constituents, paeoniflorin, trans-cinnamic acid, schisandrin and glycyrrhizin in traditional herbal medicinal preparation, So-Cheong-Ryong-Tang (SCRT). The presence of paeoniflorin, trans-cinnamic acid, schisandrin and glycyrrhizin in this decoction was ascertained by retention time, spiking with each authentic standard, UV spectrum and ESI mass spectrum. All four compounds showed good linearity (r2>0.998) in a relatively wide concentration ranges. The RSD for intra-day and inter-day precision was less than 3% and the limits of detection (LOD) were less than 30 ng. The mean recovery of each compound was 94.1-113.0% with RSD values less than 3.0%. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial SCRT products.