The aim of the study was to compare the results of the Gram-negative phytopathogenic bacteria plasmid isolation efficiency by various methods. Methods. The strains of phytopathogenic bacteria E. carotovora, A. tumefaciens, R. solanacearum were used. Plasmids isolation from the cells was carried out using alkaline Kado and Liu method, modified alkaline Kado and Liu method, modified Jensen method and Cross method. Plasmid DNA was analysed using electrophoresis in agarose gel. Results. On average, between 13% and 30% of the studied phytopathogenic strains contained extrachromosomal genetic elements. It was found that the extrachromosomal DNAs were isolated much better and bacterial chromosome was better eliminated using bacterial cells, grown on liquid selective medium (pectin or potato medium). Conclusion. The modified for phytopathogenic bacteria alkaline Kado and Liu method was the most suitable for plasmid DNA isolation from Gram-negative phytopathogenic bacteria E. carotovora, A. tumefaciens, R. solanacearum strains cells.