Chlamydia trachomatis (CT) causes a costly and potentially recurrent bacterial infection that accounts for a considerable proportion of sexually transmitted infections (STIs) in the United States. Disparities by gender and age group in CT prevalence have been reported previously. The current study evaluates demographic, socioeconomic, and behavioral risk and protective factors that may account for gender/age disparities in CT infections among sexually active young adults in the United States.Secondary analyses were performing using the 1999-2006 National Health and Nutrition Examination Survey (NHANES) data.A total sample of 5611 adults, 20-39 years of age, who participated in the 1999-2006 NHANES, reported lifetime sexual experience, and had valid laboratory-based CT status, was analyzed. CT prevalence did not differ significantly by gender and was estimated to be 1.6%. It was slightly higher for people <25 years vs. those ≥25 years of age; age disparities were reduced after controlling for demographic, socioeconomic, and behavioral characteristics. Among those <25 years, non-Hispanic blacks had a higher odds of CT infection compared with other groups. Among those ≥25 years of age, not having had unprotected sex in the past month reduced the odds for CT infection, whereas non-Hispanic black race and never married status increased the odds for CT infection.Among sexually active adults, no gender disparities were observed in CT prevalence. Age group disparities were partly explained by personal characteristics associated with risk of STIs.