BACKGROUND: The limited health and social care infrastructure that existed in the 1970s in Cambodia was destroyed due to the Khmer Rouge. Mental Health service infrastructures have developed in Cambodia in the last twenty five years, however, they have been shaped significantly by very limited funding being made available for human resources, support services and research. The lack of research on Cambodia's mental health systems and services is a significant barrier to the development of evidence-based mental health policies and practice. In order to address this barrier, effective research and development strategies are needed in Cambodia, which are based on locally well-informed research priorities. There are many possibilities for mental health research in LMIC countries such as Cambodia, therefore focused research priorities in these areas are needed to guide future research investment. This paper is the result of the development of international collaborative workshops, which focused on service mapping and research priority setting in the field of mental health in Cambodia. METHODS: A nominal group technique was used to gather ideas and insights from a range of key mental health service stakeholders in Cambodia. RESULTS: The key issues in service provisions for people with mental health issues and disorders, the interventions and programmes of support available, and currently needed, were identified. This paper also identifies five key mental health research priority areas which could form the basis for effective mental health research and development strategies in Cambodia. CONCLUSION: There is a clear need for the Cambodian government to devise a clear policy framework for health research. This framework could focus on the five research domains identified in this paper and could be incorporated within its National Health Strategic plans. The implementation of this approach would likely lead to the development of an evidence base which would allow the development of effective and sustainable strategies for mental health problem prevention and intervention. This would also contribute to promote the Cambodian government's capacity to take the deliberate, concrete, and targeted steps necessary to address the complex mental health needs of its population.