The article is devoted to standardization of raw materials of prickly lettuce or compass plant of Asteraceae family. Prickly lettuce (Lactuca serriola L.) is an annual or biennial herbaceous plant, and is widely spread in Central Black Earth region. Objective. The aim of the work was to develop the methods of identification and quantitative determination of flavonoids in the herb of prickly lettuce. Materials and methods. The investigation object was the herb of prickly lettuce stored in its blooming period in 2017-2018. The quality identification of flavonoids is based on thin-layer chromatography; the quantitative determination is based on spectrophotometric method. Results. When conducting quality identification the following conditions were established: Sorbfil plates on an aluminum substrate, the volume of application of the studied extraction - 10 μl; mobile phase: n. butanol-acetic acid-water (4:1:2), the standard substance is luteolin-7-glucoside (cynaroside); detection: treatment with 5% solution of aluminum chloride, viewing in UV light before and after treatment with aluminum chloride. Validation of the method was carried out according to the following parameters: specificity, robustness, reproducibility. For the quantitative determination of flavonoids, a spectrophotometric method of determination in terms of cynaroside, based on the reaction of complexation of flavonoids with aluminum chloride, has been developed. The optimal conditions for extracting were determined: the degree of grinding of raw material - 1 mm, the extractant - 70% ethyl alcohol, the extraction time - 30 minutes. Conclusion. The procedure has been developed for the quality identification and quantitative determination of flavonoids in the herb of prickly lettuce. The content of flavonoids ranged from 1.04 ± 0.05% to 1.58 ± 0.07%. The error of a single determination with a probability of 95% does not exceed 4.80%.