The Centre for Food Safety today banned the import of poultry products, including eggs, from Wright County in Iowa, and Lewis County in Missouri.
The ban was imposed after US authorities announced outbreaks of highly pathogenic H5N2 avian influenza in the two counties.
The centre has contacted American authorities and will monitor developments.
About 267,000 tonnes of chilled and frozen poultry meat and 530 million poultry eggs were imported to Hong Kong from the US last year.