Background Despite significant strides made in reducing malaria morbidity and mortality in the Greater Mekong Subregion, malaria transmission continues amongst the most âhard-to-reachâ such as forest-goers and mobile and migrant populations, who face access obstacles to malaria diagnosis and treatment. As such, regional malaria elimination strategies endeavour to incorporate the private sector and local communities in improving surveillance and detection of the last malaria cases in remote forested areas. The question remains, however, whether such strategies can reach these hard-to-reach populations and effectively reduce their disproportionate burden of malaria. This paper evaluates the strategy of community and private sector engagement in a malaria elimination project in Vietnam, Laos, and Cambodia.Methods Ethnographic research, incorporating in-depth interviews, participant observation with informal discussions, and group discussions were conducted in Bu Gia Map commune, Binh Phuc province of Vietnam; in Phouvong district, Attapeu province of Laos; and, in nine newly established and informal communities in the provinces of Mondul Kiri, Steung Treng, Kratie, Kampong Thom, and Prah Vihear of Cambodia. Results Different types of factors limited or enhanced the effectiveness of the participatory approaches in the different settings. In Vietnam, inter-ethnic tensions and sensitivity around forest-work negatively affected local populationâs health seeking behaviour and consequent uptake of malaria testing and treatment. In Laos, the location of the project collaborative pharmacies in the district-centre were a mismatch for reaching hard-to-reach populations in remote villages. In Cambodia, the strategy of recruiting community malaria-workers, elected by the community members, did manage to reach the remote forested areas where people visited or stayed. Conclusions âHard-to-reachâ populations remain hard to reach without proper research identifying the socio-economic-political environment and the key dynamics determining uptake in involved communities and populations. We emphasise the need for solid implementation research with a strong ethnographic component in order to tailor malaria elimination strategies to local contexts.