This study was conducted to evaluate the usefulness of the single radial haemolysis (SRH) technique for the detection of antibodies to avian influenza viruses in sera from people in the geographic regions of Pearl River Delta and Taiwan. Antibodies were found to all known avian virus haemagglutinin subtypes and populations from rural areas showed different extents of exposure from those in urban environments (p＜0.05). Additionally, people from the rural areas showed evidence of multiple infection by these avian influenza viruses. The importance of these findings is discussed in the context of the hypothesis that human pandemic influenza has its origin in a non-human species. The fact that viruses of a particular subtype are more frequently isolated from animals especially ducks is H4, and in this study antibody to the H4 subtypes were jointly the most common antibodies (except H3) detected occurring in 10% of the rural area sera.