The objective of this research is to explore what would happen if the Hong Kong influenza pandemic strain of 1968–1969 returned in 2000. We report the results of a series of simulations of an SEIR epidemic model coupled with air transportation data for 52 global cities. Preliminary results suggest that if the 1968–1969 pandemic strain returned, it would spread concurrently to cities in both the northern and southern hemispheres thereby exhibiting less of the characteristic seasonal swing. In addition, after recognition of pandemic onset in the focal city, the time lag for public health intervention is very short. These findings highlight the importance of coordinated global surveillance and pandemic planning.