Species of the genus Lathyrus L. are known as forage and medicinal plants, widely used in traditional medicine and homeopathy. The content of protein, essential amino acids and carotene in their green biomass is higher than in other annual leguminous plants traditionally cultivated in Russia. Until now, the requirements for the crop's quality were reduced to a high content of protein and dry matter in seeds and herbage. In-depth biochemical analysis of accessions from the collection of plant genetic resources will significantly improve selection of source materials for breeding. Such tasks can be solved using gas chromatography with mass spectrometry in plant diversity studies. In view of the above, our goal was to analyze organic acids, free amino acids and secondary metabolites in green biomass of Lathyrus to facilitate comprehensive assessment of its forage and pharmacological value. We analyzed 32 accessions of Lathyrus sativus L., L. tuberosus L., L. sylvestris L., L. vernus (L.) Bernh., L. latifolius L.