This study compares the efficacy ana side effects of erythromycin and azithromycin in the treatment ofchlamydial cervicitis in pregnancy. Sixty-one pregnant women DNA positive antigen for Chlamydia trachomatis were considered in two groups, one treated with erythromycin 500 mg every 6 hours for 7 days, the other with azithromycin 1 g single dose. Three weeks after therapy was started, patients were assessed for treatment efficacy, side effects and compliance, and DNA probe assay was repeated. The efficacy results were similar (93.5%/90% respectively, P=0.06), azithromycin caused fewer gastrointestinal side effects (13.3%/54.8%, p=0.01) and found better compliance. Though azithromycin and erythromycin have similar efficacy, the one has fewer side effects and better compliance than the other. Azithromycin would seem so to be a prime therapeutic for chlamydial cervicitis in pregnant women.