Approximately one-third of people who have obtained refugee status live in high-income countries. Over recent years, the number of refugees has been increasing, and there are questions on how many of them need mental health care and which type of interventions are beneficial. Meta-analyses showed highly variable rates of mental disorders in adult refugees. This variability is likely to reflect both real differences between groups and contexts, and methodological inconsistencies across studies. Overall prevalence rates after resettlement are similar to those in host populations. Only post-traumatic stress disorder (PTSD) is more prevalent in refugees. In long-term resettled refugees, rates of anxiety and depressive disorders are higher and linked to poor social integration. Research on mental health care for refugees in high-income countries has been extensive, but often of limited methodological quality and with very context-specific findings. The existing evidence suggests several general principles of good practice: promoting social integration, overcoming barriers to care, facilitating engagement with treatment and, when required, providing specific psychological treatments to deal with traumatic memories. With respect to the treatment of defined disorders, only for the treatment of PTSD there has been substantial refugee-specific research. For other diagnostic categories, the same treatment guidelines apply as to other groups. More systematic research is required to explore how precisely the general principles can be specified and implemented for different groups of refugees and in different societal contexts in host countries, and which specific interventions are beneficial and cost-effective. Such interventions may utilise new communication technologies. Of particular importance are long-term studies to identify when mental health interventions are appropriate and to assess outcomes over several years. Such research would benefit from sufficient funding, wide international collaboration and continuous learning over time and across different refugee groups.