The aim of this work was the isolation and identification of phenolic acids from fruit and leaves of Ailanthus glandulosa Desf. The methods used in the isolation and identification of the compounds were: isolation of phenolic acids modified by Ibrahim and Towers, acidic and alkaline hydrolysis by Schmidtlein and Herrmann and identification of phenolic acids in the isolated fraction of two-dimensional thin layer chromatography (TLC) on cellulose plates. In the course of the study, the presence of phenolic acids in leaves and fruit of Ailanthus glandulosa Desf was confirmed. Overall, proportions of 15 phenolic acids were found and identified in the analyzed material. These are: gallic acid, ellagic acid, caffeic acid, gentisic acid, protocatechuic acid, p-hydroxybenzoic acid, m-hydroxybenzoic acid, ferulic acid, p-coumaric acid, syryngic acid, vanillic acid, salicylic acid, 2-hydroxy-4- methoxybenzoic acid, 2,5-dimethoxycinnamic, p-hydroxyphenylacetic acid, and 3 other compounds named A, B, C, whose identification was not possible due to the lack of suitable reference patterns. Studies have shown that leaves and fruit of the plant Ailanthus glandulosa Desf. contain a large number of phenolic acids which possess many important pharmacological activities.