Between January and March 1971, an unusual outbreak of hemorrhagic fever occurred in Cochabamba, Bolivia. The index case was apparently infected elsewhere, but became ill in Cochabamba, where hemorrhagic fever had never been reported. Four secondary cases occurred among hospital contacts of the index case, and a pathologist was infected after cutting himself during an autopsy of one of the secondary cases. Clinical manifestations were typical of Bolivian hemorrhagic fever, except that jaundice occurred in three cases. An arenavirus of the Tacaribe complex was isolated from three cases. One isolate was studied in detail and shown to be closely related antigenically to the prototype strains of Machupo virus.