In vitro antibacterial activity of the new macrolide azithromycin was tested against 116 strains of Brucella melitensis, isolated from 115 patients in a major tertiary care referral center. Eighty-seven percent of the strains were inhibited by 1.0 mg/l and all the 116 strains by 2.0 mg/l of azithromycin. Comparison was made with tetracycline, gentamicin, trimethoprim-sulfamethoxazole, rifampicin and ciprofloxacin. All the isolates were susceptible to gentamicin, tetracycline, trimethoprim-sulfamethoxazole, rifampicin. One hundred and fifteen of the 115 strains were also susceptible to ciprofloxacin.