Dried parts of the herb medicines are difficult to distinguish morphologically. Heracleum moellendorffii cordata has often been sold instead of Aralia cordata in herbal medicine markets. Therefore, this study was conducted to develop the key for discrimination between them using the RAPD analysis and morphological characteristics. Thirty decarmer oligonucleotide primers were screened for the RAPD analysis, and four primers generated distinct RAPD markers specific to Aralia cordata, Angelica pubescens maxim f. biserrata, and Heracleum moellendorffii. The specific RAPD patterns generated by the selected primers were reproducible from dried materials. In comparison of morphological characteristics, Aralia cordata seems to be entirely developed in xylem fiber, but not developed in pith.