In Cambodia, 85% of farmers are rice producers. Organic rice production has been adopted, with non-government organisation support and certifications, to improve farmers' revenue for sustainable rural development. This study aims to define the constraints of organic rice adoption in an agro-ecosystem with high risk of flood. Using agrarian system diagnosis and analysis, it is found in the study that organic rice gives high value-added per hectare but low value-added per family labour because of the less non-flooded surface available to avoid chemical contamination, to enlarge organic rice surface. Moreover, organic farmers face lower social status because organic production practices are viewed as old-fashioned tools use by the poor farmers and that will not help them escape poverty. Another institutional constraint is that organic farmers face late payment from their cooperative until the rice is on-sold. This study finds that the price premium for organic rice is not high enough to induce adoption of this cropping practice. However, organic farmers are well trained, produce high-quality rice and are model farmers who participate in policy-making events, which encourage them to continue to produce organic rice.