It is vital to strengthen the capacity of communities and countries to prepare and adapt to the health impacts arising from climate change. Capacity can be strengthened by increasing the understanding, knowledge and skills of individuals within the health sector as well as with other sectors relevant to health. Important knowledge areas include the basics of climate change science, the fundamental links between climate change and human health, and more specific areas of focus, including epidemiology and health information system strengthening. Currently, no comprehensive and regional-wide training program exists that intensively develops the knowledge and understanding of the health sector. The objective of this activity in Vietnam, Cambodia and Lao PDR was to i) support a core group of staff within each country to develop and strengthen their understanding of the links between climate change and human health and ii) for this group to be able to sustain this knowledge and train their peers (Training of Trainers approach) in their home countries. 17 participants in each country were identified for this intensive regional TOT ‘Fellowship’. Participants represented the health and non-health sectors, including meteorology, agriculture, disaster management. The training occurred over three separate occasions throughout 2017/2018. The phased training allowed participants to work on a small group research project that was closely related to the project during the periods between training. Participants were supported to rollout the training at both national and provincial levels (and potentially beyond) once the ToT Fellowship was concluded (January, 2018). Provinces were selected in each country after the national rollout training was conducted. ToT Fellows who were selected to participate in the training were highly engaged, enthusiastic and willing to learn more about climate change and human health. The iterative development and conduct of the training served to provide an opportunity to evaluate and adapt the training through the process, which lead to a more tailored result. The Greater Mekong Sub-region is now in the process of developing a sustainable cadre of health and climate change champions, who have the ability to train their country colleagues on the links between climate change and human health, and appropriate ways to respond and reduce the related impacts. In addition, the regional approach has allowed skill-sharing and knowledge exchange between countries, with this increased knowledge, skill, and understanding, the health sector is in a much stronger position to prepare and implement relevant policies and activities to safeguard human health.