BACKGROUND: The extent of adherence to the Centers for Disease Control and Prevention (CDC) STD guidelines by clinicians practicing in managed care settings is unknown. GOAL The goal was to assess adherence to the CDC guideline recommendations for the treatment of genital chlamydial infection, by clinicians at two group model managed care organizations. DESIGN: Retrospective cohort study of men and women with laboratory-confirmed chlamydial infection. Patients were members of either the Kaiser Permanente Foundation Health Plan of Colorado or HealthPartners of Minneapolis/St. Paul who had tested positive for cervical or urethral chlamydial infection during the period from January 1, 1998, through June 30, 1999. RESULTS: During the study period, 1,078 patients with positive tests for genital Chlamydia trachomatis were identified. More than 97% of men and nonpregnant women and more than 98% of pregnant women were prescribed treatment, consistent with current CDC guidelines. CONCLUSION: Adherence to CDC-recommended therapy was high for patients with genital chlamydial infections at these two managed care organizations.