Objective:The objective of this study was to investigate a large outbreak of shigellosis in Papua New Guinea that began in a camp for internally displaced persons before spreading throughout the general community.Methods:Outbreak mitigation strategies were implemented in the affected area to curtail the spread of the disease. Data were collected from the surveillance system and analysed by time, place and person. Rectal swab samples were tested by standard culture methods and real-time polymerase chain reaction to determine the etiology of the outbreak.Results:Laboratory analysis at two independent institutions established that the outbreak was caused by Shigella sp., with one strain further characterized as Shigella flexneri serotype 2. Approximately 1200 suspected cases of shigellosis were reported in a two-month period from two townships in Morobe Province, Papua New Guinea. The outbreak resulted in at least five deaths, all in young children.Discussion:This outbreak of shigellosis highlights the threat of enteric diseases to vulnerable populations such as internally displaced persons in Papua New Guinea, as has been observed in other global settings.