The present paper deals with study of mutants resistants against five antibiotics in a phytopathogenic bacterium Xanthomonas campestris (Pammel) Dowson. One-step mutants to streptomycin and erythromycin were isolated. For the penicillin, aureomycin and chloranphenicol multiple-step mutants appeared the sensitive populations were grown in gradient plates with antibiotics. The resistance increase was 4 fold for the penicillin, 8 fold for the chloranphenicol, 32 fold for the aureomycin; 16 fold for the erythromycin and 128 fold for the streptomycin. It was not found cross resistance or collateral sensitivity when a certain antibiotic was tested against the others drugs.