Gram-negative plant pathogenic bacteria are secreting into plant cell a special type of pathogeni city-related proteins called effectors. They are capable of suppressing plant innate immunity or stimulating synthesis and export of metabolites desired by the pathogen. We identified a number of effector-coding genes typical of xanthomonads analyzing 8 completely sequenced genomes of genus Xanthomonas. Using representative collection provided by Russian Research Institute of Phytopathology we identified genetic diversity of effector gene loci in population of Xanthomonas bacteria. Patterns of effector genes were identified for individual strains and statistic linkage between particular genes and race of the pathogen was established. For the first time several untypical effector genes were found in strains of Xanthomonas campestris pv. campestris.