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 ($r^2$ > 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.