A community-based surveillance system was developed and implemented in rural areas in Cambodia. The system aimed to provide timely and representative information on major health problems and life events that would permit rapid and effective control of outbreaks and communicable diseases in general in rural communities. In the system, lay people were trained as Village Health Volunteers to report suspected outbreaks, important infectious diseases, and vital events occurring in their communities to local health staff who analysed the data and gave feedback to the volunteers during their monthly meetings. An evaluation conducted one year after implementation of the community-based surveillance system began found that the system was able to detect outbreaks early, regularly monitor communicable disease trends, and to continuously provide updated information on pregnancies, births and deaths in the rural areas. The sensitivity and specificity of case reporting by Village Health Volunteers were found to be quite high. In addition, the community-based surveillance system triggered effective responses from both health staff and Village Health Volunteers in outbreak and disease control and prevention. The results suggest that a community-based surveillance system can successfully fill the gaps of the current health facility-based disease surveillance system in the rapid detection of outbreaks, in the effective monitoring of communicable diseases, and in the notification of vital events in rural Cambodia. Empowered local people and health staff can accurately report, analyse and act upon significant health problems in their community within a surveillance system they develop, own and operate. The community-based surveillance system could easily be integrated with the current disease surveillance system. Its replication or adaptation for use in other rural areas in Cambodia and in other developing countries would be likely feasible and beneficial, as well as cost-effective.