The genus Persicaria Mill. species belonging to the buckwheat family (Polygonaceae Juss.) and widespread in Russia, are weeds. The chemical composition’s main components of the genus Persicaria Mill. species, are flavonoid glycosides (rutin, avicularin, hyperoside, etc.). The data concerning a comparative study of the organic acids in the herb representatives of genus Persicaria Mill., have not been detected in the available literature.The aim of the research is a comparative study of the organic acids qualitative and quantitative composition in the genus Persicaria Mill. species growing in the Voronezh region.Materials and methods. The objects of the study were dried herb samples of the genus Persicaria Mill. species. All the species were harvested in the Voronezh region during the blooming period. The quantitative content of ascorbic acid and the amount of organic acids in terms of malic (hydroxy-succinic) acid was carried out according to the titrimetric methods of the Russian Federation State Pharmacopeia, the XIVth ed. The study of the qualitative composition of the organic acids profile and their quantitative content assessment in the studied objects, the herbs, was carried out by the method of capillary electrophoresis (“Kapel”, St. Petersburg, Russia).Results. With the help of pharmacopoeial titrimetric methods, it was established that the highest content of the organic acids total amount is characteristic of the Persicaria maculosa Mill. herb (5,60%), the lowest one – of the Persicaria tomentósa (Schrank) E. P. Bicknell herb (4.03%). Persicaria maculosa S. F. Gray and Persicaria hydropiper (L.) Delarbre are the richest in ascorbic acid (0.17% and 0.15%, respectively). Using the method of capillary electrophoresis, the composition of the total amount of the studied organic acids has been established. It is represented by oxalic, formic, citric, malic, wine, propionic, lactic, benzoic and other acids.Conclusion. The study of the organic acids of the genus Persicaria Mill. species has been carried out. It has been established that in the studied species, the organic acids total amount in terms of malic acid and the amount of ascorbic acid are similar. By the method of capillary electrophoresis, a complete composition of organic acids has been studied, and the quantitative content of each component has been established. In all the studied Persicaria Mill. species, the predominance of oxalic, formic and malic acids has been revealed.