Between May and December 2004,Yap State experienced an outbreak of Dengue Fever, type 1 with a final total of 658 recorded clinically compatible cases, including 42 hospitalisations and 12 cases of dengue haemorrhagic fever/shock syndrome. There were no fatalities. Lessons learned from this outbreak include: the importance maintaining a high index of suspicion and on-site diagnostic capability for dengue fever, the importance of prompt in-service training for health care workers, the danger posed to neighbors by local lapses in outbreak prone disease surveillance and the utility of the Pacific Public Health Surveillance Network in responding to such diseases, the importance of active disease surveillance in outer island populations, and the importance of instituting preventive measures against the nosocomial spread of dengue fever.