Background Technological advances offer opportunities to redesign existing chlamydia screening and testing, and treatment pathways, to improve screening uptake and the proportion of positive individuals successfully treated. Innovations underway include self-tests networked through mobile phones, which could be combined with online clinical care and other non-face-to-face care pathways. Evidence of young people's preferences should be key to informing optimum service redesign. We aimed to quantify factors affecting young people's preferences for emerging chlamydia testing and treatment pathway options in a discrete choice experiment (DCE). Methods Methods used to select attributes and levels for the DCE included a systematic literature review, four focus groups (staged recruitment to include spread in age range 16–24 years and other demographic characteristics), and four expert groups of clinicians and researchers. The literature review sought stated preference studies for testing and treatment of sexually transmitted infections (STI) published before Dec 31, 2015. Studies were published in English, and included one or more aspects of mainstream STI testing and treatment for any STI, undertaken in an Organisation for Economic Co-operation and Development high-income country. Key search terms included stated preference, stated choice, DCE, contingent valuation, and conjoint analysis. A draft questionnaire was tested in a pilot (n=9). The final questionnaire (including 25 pairwise choices with opt-out) was completed online by a national panel of young people aged 16–24 years across England (YouthSight). Analysis used multinomial logit models and included validity checks. Findings There were 1230 respondents (response rate 73%). The strongest attribute affecting preferences was chlamydia test accuracy (odds ratio [OR] 3·24, 95% CI 3·13–3·36), followed by time to result (1·81, 1·71–1·91). Respondents showed a preference for remote chlamydia testing options (self-testing, self-sampling, postal testing) over attendance at a testing location. A general preference for accessing treatment was observed for online (OR 1·21, 95% CI 1·15–1·28) versus traditional general practice (1·18, 1·12–1·24), pharmacy (1·15, 1·10–1·22), or clinic (OR 1) services. Little difference was observed between face-to-face, telephone, instant messaging or email methods of access. No significant difference in preferences was seen for antibiotic provision (eg, collection from pharmacy vs postal delivery). Interpretation DCE coefficients can help estimate uptake probabilities for redesigned chlamydia pathways. Although this DCE was conducted in an online population, which might limit generalisabiity to other populations, findings could assist technology developers, policy makers, commissioners, and service providers to optimise the adoption of emerging technologies and service redesign.