This work aimed to study the chemical composition of the crystalline mass obtained from the acetone extract of the roots of Lactuca serriola L. Its characterization by gas chromatography-mass spectrometry (GC-MS) analyses led to the identification of 21 substances including palmitic acid, methyl ester, n–hexadecanoic acid, methyl-trans-oleate, 11-octadecenoic acid methyl ester, methyl stearate, oleic acid, 11-eicosenoic acid methyl ester, common in the most plant species. Furthermore, some triterpenoid compounds [olean-12-en-3-one, 13,27-cycloursan-3-one, ursa-9(11),12-dien-3-yl acetate, lupeol, germanicol, lup-20(29)-en-3-ol, acetate, (3β)] characteristic of the L. serriola were identified. Despite the richness of chemical composition and the wide availability in Azerbaijani flora, L. serriola is still uninvestigated. Therefore, the study of the qualitative and quantitative composition of this plant represent interest.