BackgroundPartner notification is the process of providing support for, informing and treating sexual partners of individuals who have been diagnosed with sexually transmitted infections (STIs). It is traditionally undertaken by specialist sexual health services, and may involve informing a partner on a patient’s behalf, with consent. With an increasing proportion of STIs diagnosed in general practice and other community settings, there is a growing need to understand the best way to provide partner notification for people diagnosed with a STI in this setting using a web-based referral system.ObjectiveWe aimed to compare three different approaches to partner notification for people diagnosed with chlamydia within general practice.DesignCluster randomised controlled trial.SettingGeneral practices in England and, within these, patients tested for and diagnosed with genital chlamydia or other bacterial STIs in that setting using a web-based referral system.InterventionsThree different approaches to partner notification: patient referral alone, or the additional offer of either provider referral or contract referral.Main outcome measures(1) Number of main partners per index patient treated for chlamydia and/or gonorrhoea/non-specific urethritis/pelvic inflammatory disease; and (2) proportion of index patients testing negative for the relevant STI at 3 months.ResultsAs testing rates for chlamydia were far lower than expected, we were unable to scale up the trial, which was concluded at pilot stage. We are not able to answer the original research question. We present the results of the work undertaken to improve recruitment to similar studies requiring opportunistic recruitment of young people in general practice. We were unable to standardise provider and contract referral separately; however, we also present results of qualitative work aimed at optimising these interventions.ConclusionsExternal recruitment may be required to facilitate the recruitment of young people to research in general practice, especially in sensitive areas, because of specific barriers experienced by general practice staff. Costs need to be taken into account together with feasibility considerations. Partner notification interventions for bacterial STIs may not be clearly separable into the three categories of patient, provider and contract referral. Future research is needed to operationalise the approaches of provider and contract partner notification if future trials are to provide generalisable information.Trial registrationCurrent Controlled Trials ISRCTN24160819.FundingThis project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 19, No. 5. See the NIHR Journals Library website for further project information.