Plants known as rhubarb synthesize anthraquinones and tannins. Theses compounds have medicinal uses as laxative and astringent, respectivity. The quality of five raw materials was analysed to detect adulterant. Anthraquinones and tannins reactions were positive. Derivatives rhapontocoside were observed in the sample of Rheum palmatum (2). Total ashes were increased to Rheum palmatum (2) and Ferraria cathartica. According to the results, samples of Rheum palmatum (2) and Ferraria cathartica shoulde are adulterated.