An electrochemical method for analysing sequence-specific fragments of genes from Listeria monocytogenes and genetically-modified components in food is presented. This method was applied for the detection of listeriolysin (hlyA) gene, present only in pathogen strains of L. monocytogenes and phosphotransferase neomycine (nptII) gene coding for neomycin/kanamycin resistance, which is often utilized for the production of transgenic plants. The analytical procedure gene coding for neomycin/kanamycin resistance, which is often utilized for the production of transgenic plants. The analytical procedure nptII consisted of four steps: single-stranded DNA (ssDNA) probe immobilization at the controlled potential of +0.5 V on the surface of carbon paste electrode (CPE); hybridization between the immobilized probe and the target complementary sequence in the sample; association of double-stranded (dsDNA) binding compounds (daunomycin and methylene blue), and amperometric detection by square-wave voltammetry.