The emergence and spread of Highly Pathogenic Avian Influenza H5N1 has caused substantial poultry-related economic losses and public health concerns in relation to a potential pandemic. While biosecurity measures for commercial poultry industry are of the highest standards, these measures are difficult to implement and often unaffordable for backyard poultry farming, particularly in tropical and low-income settings. We designed a feasible biosecurity intervention to improve flock hygiene in Cambodia, - based on community hygiene, cleaning of poultry flock areas and human and poultry movement control. We conducted a cluster randomized and controlled intervention trial in 18 villages in Takeo province to evaluate improvements in biosecurity-related knowledge and practices. The intervention relied on community involvement and community education using special information dissemination tools. We trained village teams (VT) to assist villagers in implementing the intervention using a cascade training approach, in which a few individuals were trained, who in turn trained a larger group of people. During the 14 month follow up, we conducted observational and interview-based surveys (baseline vs. final surveys, VT supervision visits, monitoring surveys) to assess VTs' motivation, intervention messages dissemination and the implementation of recommended measures. Most of villagers (95%, confidence interval: 87.8-100.0%) in intervention villages received general information about how to raise poultry. Farmers in intervention villages reported to have made more changes (?1 biosecurity related practice during the study period) compared with that of control villages (70.0% (260/372) vs. 22.6% (85/377), p value. <. 0.01). When observing biosecurity-related practices in intervention villages, overall scores increased significantly (p<. 0.05). Practices such as use of quarantine cages for new and sick birds, limitation of people movement in backyards and waste management reach