Highly Pathogenic Avian Influenza H5N1 epizooty started in Vietnam late 2003 and resulted into more than 50 millions poultry culled and 93 human cases (42 fatal cases). In 2005, the Government decided to apply a mass vaccination campaign to limit virus circulation and to reduce the threat to human health. Then, neither outbreaks in poultry nor in human have been notified for about one year. With a majority of poultry vaccinated in the higher risk areas, the clinical expression of H5N1 inevitably changed and as a result the surveillance approach should be adapted. Routine virological surveillance and recent outbreaks showed that virus is still circulating. Within a FAO project funded by Japanese Government, a model is tested to strengthen the surveillance of H5N1 infection among backyard and commercial poultry. This model was designed to increase the detection and the notification of suspect poultry health events that could be avian influenza. An awareness campaign explained to key stakeholders that due to vaccination, criteria to detect a H5N1 outbreak should change. A targeted surveillance programme is also tested including a disease-free certification for vaccinated semi-commercial broilers farms and an active community animal disease surveillance component in selected villages. The methodogy of this surveillance model and preliminary results are presented.