Feasibility, acceptability and impact of an innovative, tailored HIV prevention intervention for MSM at high-risk of HIV in Indonesia. Despite significant progress in HIV management and prevention, 1.8 million new HIV infections were recorded worldwide in 2016, with many settings observing increasing numbers of new HIV infections, predominantly in key affected populations.   Despite the development of revolutionary evidence-based HIV prevention interventions, combating the HIV/AIDS epidemic still remains a major global health challenge.  Key populations groups, namely, men who have sex with men (MSM), transgender people, people who inject drugs, prisoners and sex workers, are at greatest risk of being affected by HIV and they frequently lack adequate access to appropriate services.  Stigma and discrimination are among the primary barriers to HIV prevention, treatment and support; key populations in particular face significant stigma in many settings. Indonesia has the third largest number of people living with HIV (PLWH) in Asia and the Pacific; with 620,000 PLWH and 48,000 new infections recorded in 2016.  Key populations are most affected and at greatest risk of HIV.  In 2016, HIV prevalence estimates were 25.8% in MSM (compared to 8.5% in 2011), new infections are increasing significantly and rapidly in MSM in Indonesia but more reportedly stable in other key populations. In major cities Denpasar in Bali and Jakarta, nearly one in three MSM are infected with HIV.   Indonesia is observing worsening stigma and discrimination against MSM, transgender people and PLWH which is significantly slowing the country's HIV response. This rise in anti- LGBT rhetoric adds great challenges of allowing a human rights-based approach to sexual health care and HIV prevention to hard-to-reach key populations and counteracting HIV prevention and treatment targets.  Innovative and sensitive methods of engaging at risk communities to improve access and uptake to services, without increasing their vulnerability to abuse, are greatly needed.  Tailored mobile phone, internet-based programs may be a critical way to engage key populations like MSM who are understood to be a technologically/mobile smartphone literate population.  We propose a tailored, innovative HIV prevention model to strengthen HIV prevention services and accelerate the response to a growing burden of HIV in MSM, in Indonesia.  A model appropriately adapted through at-risk population engagement, from one that has demonstrated success in dramatically reducing new HIV infections in MSM in London. We propose assessing the feasibility, acceptability and impact of; (1)   a mobile-phone text-message based digital-health HIV risk-reduction intervention, tailored to the MSM population at high risk of HIV in Indonesia; developed through at-risk population engagement and needs assessment.  (2) integrating point of care/rapid HIV and HIV monitoring diagnostics in an existing sexual-healthcare service, to also determine the proportion of very early HIV acquisition in new HIV diagnoses to further guide HIV treatment and prevention. (3) integrating evidence-based prevention interventions - immediate antiretroviral treatment as prevention to all individuals recently diagnosed/living with HIV and oral Pre-Exposure Prophylaxis provision (a proven HIV preventative medicine) to MSM at risk of HIV in an existing sexual-healthcare service.  Can the prevention model have an impact on; increasing HIV testing coverage in MSM at risk of HIV; reduce undiagnosed and late diagnoses of HIV infection in this at-risk population; have an impact on reducing new HIV infections and improve retention in HIV care and antiretroviral treatment (ART) adherence in people diagnosed and living with HIV.  Ultimately to contribute to the UNAIDS/WHO goals in ending AIDS as a global public health threat in this region, to aid disease prevention and improve health in this population and consequently have economic benefits for the country as a whole. The Newton Fund builds research and innovation partnerships with developing countries across the world to promote the economic development and social welfare of the partner countries.