BackgroundGonorrhea and chlamydia are the most common sexually transmitted diseases (STDs) among men who have sex with men (MSM) in China. Previous studies have shown pay-it-forward (PIF) interventions to be associated with a substantial increase in gonorrhea and chlamydia test uptake compared to standard-of-care. We propose a 'pay-it-forward' gonorrhea and chlamydia testing randomized controlled trial (PIONEER). The trial would evaluate the effectiveness of two pay-it-forward strategies in promoting testing uptake compared to the standard of care (in which men pay for their tests out-of-pocket) among MSM and male STD patients in China.MethodsPIONEER will be a three-armed, pragmatic cluster randomized controlled trial (RCT), conducted across 12 clinics (six MSM-led and six public STD clinics) to compare the effectiveness of three implementation strategies. Each facility will be randomized to a standard pay-it-forward intervention of gonorrhea/ chlamydia testing with minimal encouragement for testing, a community-engaged pay-it-forward arm, or a control arm where men pay for their tests out-of-pockets. The primary outcome will be dual gonorrhea/chlamydia test uptake. Secondary outcomes will include syphilis testing, amount donated in pay-it-forward, number of positive gonorrhea and chlamydia tests, and measures of antimicrobial resistance. A sequential transformative mixed methods design will be used to evaluate the implementation process in type 2 effectiveness-implementation hybrid design. Data sources will include survey on acceptability, and feelings and attitudes towards the interventions among participants; testing and treatment uptake data from clinic records, WeChat records, and qualitative data to gain insights into men's perceptions and attitudes towards the pay-it-forward, mechanisms driving uptake, and donating behaviors. Implementers and organizers will be interviewed about fidelity and adherence to protocol, sustainability of pay-it-forward intervention, and barriers and facilitators of implementing the intervention.DiscussionPIONEER will substantially increase gonorrhea/chlamydia testing among MSM in China, providing an innovative and new financial mechanism to sustain STD screening among sexual minorities in low- and middle-income countries. This study will answer compelling scientific questions about how best to implement pay-it-forward and the individual and organizational characteristics that moderate it.Trial registration: The study with identification number NCT05723263 has been registered on clinicaltrials.gov/.