Background: Chlamydia trachomatis is the most common reportable sexually transmitted infection in the United States, with >60% of reported cases occurring in individuals aged 15 to 24 years. US practice guidelines recommend directly observed therapy (DOT) for the treatment of chlamydia in adolescents, but almost no research has been done to evaluate whether DOT results in improved outcomes. Methods:We conducted a retrospective cohort study of adolescents who sought care at 1 of 3 clinics within a large academic pediatric health system for a chlamydia infection. The study outcome was return for retesting within 6 months. Unadjusted analyses were performed using χ 2 , Mann-Whitney U, and t tests, and adjusted analyses were performed using multivariable logistic regression.Results: Of the 1970 individuals included in the analysis, 1660 (84.3%) received DOT and 310 (15.7%) had a prescription sent to a pharmacy. The population was primarily Black/African American (95.7%) and female (78.2%). After controlling for confounders, individuals who had a prescription sent to a pharmacy were 49% (95% confidence interval, 31%-62%) less likely than individuals who received DOT to return for retesting within 6 months.Conclusions: Despite clinical guidelines recommending the use of DOT for chlamydia treatment in adolescents, this is the first study to describe the association between DOT and an increase in the number of adolescents and young adults who return for sexually transmitted infection retesting within 6 months. Further research is needed to confirm this finding in diverse populations and explore nontraditional settings for the provision of DOT.