Features of 318 cases of dengue fever occurring in army personnel during an epidemic on a South Pacific island are presented. Aedes aegypti was the most efficient vector. Onset of symptoms was sudden in 93% of the cases, and followed an incubation period of 6-10 days. Frontal headache, generalized aches and pains, along with fever and chills were dominant symptoms. The temp. curve was of the saddle-backed var. in 66% of the cases. A rash was present in 37%. All cases had a leukopenia and a Schilling shift to the left. All responded to symptomatic treatment.