Hong Kong on Saturday confirmed two more cases of swine flu to bring the territory's total to six.
Thomas Tsang of the city's Center for Health Protection said the two latest patients are a mainland Chinese man from San Francisco and a 20-year-old Hong Kong woman who was studying in New York.
Both are in stable condition at a local hospital.
Their infections were detected by temperature sensors at the territory's airport Friday night after the two arrived from the US.
The first case involving a Mexican man led authorities to quarantine hundreds of people at an upscale hotel earlier this month.