OBJECTIVE: Child sexual exploitation (CSE) can be difficult to identify, as there may be few reliable indicators. Although they may be used in decision-making, there is no evidence that STIs are predictors of CSE. We investigated the relationship between STI presentation at sexual health clinics (SHCs) and CSE. METHODS: SHCs with 18 or more children aged 13-15 years old with STI diagnoses in 2012 were identified using the Genitourinary Medicine Clinic Activity Data Set STI Surveillance System. Cases with confirmed bacterial or protozoal STIs were matched by age, gender and clinic with non-STI controls. Lead clinicians were asked to complete an online questionnaire on CSE-related risk factors of cases and controls irrespective of STI presence. Associations between STI outcome and CSE-related risk factors were analysed using conditional logistic regression. RESULTS: Data were provided on 466 children aged 13-15 years old; 414 (89%) were female, 340 (80%) were aged 15, 108 (23%) were aged 14, and 18 (3.9%) were aged 13 years. In matched univariate analysis, an STI diagnosis was significantly associated with 'highly-likely/confirmed' CSE (OR 3.87, p=0.017) and safeguarding concerns (OR 1.94, p=0.022). Evidence of an association between STI diagnosis and 'highly-likely/confirmed' CSE persisted after adjustment for partner numbers and prior clinic attendance (OR 3.85, p=0.053). CONCLUSION: Presentation with bacterial or protozoal STIs in children aged 13-15 years old at SHCs may be considered a potential marker for CSE. It would be prudent to consider CSE, indepth assessment and potential referral for any children under 16 years old presenting with a bacterial or protozoal STI.