To prepare the 2001 sexually transmitted disease treatment guidelines of the Centers for Disease Control and Prevention, recently published articles and abstracts concerning advances in the treatment of uncomplicated Chlamydia trachomatis genital infections in adults were reviewed. Questions about treatments were posed and answered according to the results of efficacy studies and clinical trials. Recent studies have continued to demonstrate the similar efficacy of doxycycline and azithromycin. Because compliance with doxycyline remains a concern, administration of single-dose azithromycin therapy in the clinic presents a potential advantage for patients whose adherence is questionable. Because few systematically collected data have been published concerning the safety and efficacy of azithromycin use in pregnancy, the guidelines continue to recommend treatment with erythromycin or amoxicillin. Nevertheless, because of azithromycin's less frequent side effects and improved adherence, increasing numbers of obstetricians in the United States are using azithromyin to treat pregnant women with uncomplicated C. trachomatis infections.