Following a study modelling the geographical spread of influenza in France, on the basis of population movements through the use of railroad data, we applied the same methodology on a European scale. We simulated an epidemic within a network of 9 European cities (Amsterdam, Berlin, Budapest, Copenhagen, London, Madrid, Milano, Paris, Stockholm), only taking into account regular between-cities air transport. Transportation data were obtained from the International Civil Aviation Organization (1991). The theoretical results show that the time lag for action is probably short (less than one month) after the first detection of an epidemic focus.