Background. Legumes establish symbioses with nitrogen-fixing bacteria from the Rhizobium group. In exchange for nutrients, bacteria provide fixed nitrogen needed to support plant growth. At the moment, information about the involvement of alternative splicing (AS) in the establishment and maintenance this symbiotic relationships is almost absent, but, as it is a powerful mechanism for the regulation of proteome diversity of the cell, it therefore may participate in cellular response to microsymbionts. Materials and methods. Alternative splicing was analyzed using the assembly of “supertranscripts” and alignment of the reads from nodules and root tips to this reference. Target genes expression levels was estimated in tips of non-inoculated roots, and in nodules (2, 4, and 6 weeks post inoculation) with use of RT-qPCR. Results.In this study, the analysis of AS events in the nodules and root tips of the pea was carried out. The presence of isoforms of four pea genes (PsSIP1, PsIGN, PsWRKY40, PsPR-10) was confirmed and their expression level was estimated. Conclusion. Pea nodules were shown to be more enriched with AS events compared to root tips. Among the functional groups of genes that demonstrate AS events, one of the most enriched functional groups is the pathogens stress response. Intron retention probably leads to degradation of the transcript via NMD-system or to change of the protein function, that modulates the activity of genes in nodules.