During 2000, the millennium year, 26 million people visited Rome. An improved surveillance system for infectious diseases, especially for foodborne disease outbreaks (FBDO), meningitis, and legionnaires' disease was introduced in 1997. This rapid alert network links public health services with the principal sources of diagnosis and laboratory based surveillance. For travel related legionnaires' disease, international surveillance was implemented. Specific control measures for FBDOs were adopted. No increase in the overall incidence of these diseases was observed, and no atypical pathogens in FBDOs or meningitis were isolated in 2000 relating to 1998-99. Cases of legionnaires' disease and FBDOs involving foreign tourists increased (10/4 and 7/2 observed/expected respectively). Three out of six FBDOs involving pilgrims occurred in religious guesthouses. While an increase in cases of legionnaires' disease and FBDOs among foreign tourists was observed by the surveillance system, the millennium year did not influence the epidemiology of infectious diseases in the residential population of Lazio.