A program for routine health surveillance on international cruise ships visiting the Port of Sydney has been developed since 1998. Before introduction of this program, ships only reported quarantinable diseases and were not aware of the Australian requirement to report other infectious diseases. Voluntary routine reporting, developed in partnership with the cruise ship industry, provides timely information on all infectious diseases of public health interest during every cruise. During 1999-2003, the program resulted in detection of and response to 14 outbreaks of gastroenteritis or acute respiratory infection, affecting more than 1400 passengers and crew. The program has improved preventive action, and risk communication and management by cruise ship operators, and led to more timely investigation and support by public health authorities.