From the processed semen of 353 bulls, 137 antibiotic resistant bacterial strains were isolated. 124 strains were penicillin and 89 streptomycin resistant. Bacteria isolated from fresh semen were examined for penicillin, streptomycin and gentamycin resistance, then semen was conserved (penicillin and streptomycin were added) and then the resistance of reisolated bacterial strains to penicillin, streptomycin and gentamycin was evaluated. From the fresh semen 21 penicillin and 9 streptomycin resistant strains were isolated. However, from these same samples of semen afer thawing 10 bacterial strains resistant to penicillin and 6 strains resistant to streptomycin were reisolated. All isolated bacterial strains were gentamycin sensitive.