Rhubarb (Rhei Rhizoma) has been used for the various clinical purposes such as purgative, stomach protective and pain relief for a long time. However, rhubarb in current market has a problem of quality control under which many of rhubarb fail to meet the standard specified in Korean Pharmacopoeia. This study was carried out to validate the method for the evaluation of the quality of five rhubarbs and Rumex species; Rheum palmatum, R. officinale, R. tanguticum, R. franzenbachii, R. undulatum, and Rumex species. The content of sennoside A with five anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) in five rhubarbs and one Rumex has been performed by using HPLC quantitation analysis. In results, only four samples in Palmata sect. were qualified with sennoside A and those samples were R. officinale and R. tanguticum. Samples of R. palmatum did not meet the standard contents of sennoside A. The contents of anthraquinones in Palmata sect. were two times larger than those in Rhapontica sect. Moreover the content variations of anthraquinones were smaller than those of sennoside A. Thus, anthraquinones can be the key characterizing molecules to control quality of rhubarb.