Policy brief. Globally, one in five people with HIV are unaware of their status, despite considerable scale up of HIV testing, treatment and prevention services. Many of those unreached by HIV testing services (HTS) are from key populations, partners of people with HIV and, in Eastern and southern Africa, men and young people. Improving the availability, accessibility, friendliness and quality of services is important to address these testing gaps. At the same time, tools and interventions that increase the demand for HTS are needed to reach people who are uninformed about HTS options and advances in treatment and prevention, people who are not motivated to seek HTS and those who are hesitant to test because of fear of an HIV diagnosis or other reasons.