An open, noncomparative study was performed to establish the efficacy of azithromycin in the treatment of early syphilis. Sixteen patients were treated with oral azithromycin: 1g the first day and then 500 mg for the following 8 days. Two patients were excluded from the study, leaving 14 patients for the evaluation of the efficacy. Venereal Disease Research Laboratory (VDRL) negativity was observed in 3 out of 6 patients treated for primary syphilis after 3 months and in all patients after 6 months. Two of 8 patients treated for manifest or early latent secondary syphilis had VDRL negativity after 3 months and 4 patients after 6 months. This study demonstrates that azithromycin is effective in the treatment of early syphilis. Two patients experienced gastrointestinal side effects which did not require treatment interruption.