An explosive epidemic of dengue occurred in Fiji between January and July 1975. All laboratory evidence indicated that type 1 dengue was the only prevalent dengue virus. This type had probably not been in Fiji for 30 years and over 70% of the population was susceptible. Aedes aegypti appeared to be the major vector in urban areas, but circumstantial evidence indicated that Aedes rotumae was a vector in at least one remote area. All forms of the clinical spectrum of dengue were seen and reported in all age groups. Overt clinical symptoms tended to be less frequent among children under age 10 and adults over age 30. Approximately 16% of persons reporting dengue-like illness had some type of bleeding associated with their disease with little difference by age, sex, or ethnic group. Epistaxis and gingival bleeding were the most commonly reported and observed hemorrhagic manifestations, but internal bleeding was reported in about 25% of hemorrhagic cases. The proportion of hemorrhagic cases was the same among primary and secondary dengue-infected persons. These and other epidemiologic observations did not support the hypothesis that the hemorrhagic complications seen with dengue occur only in secondary infections.