In late 1984, 10 children in a small, rural town in Brazil had high fever associated with vomiting and abdominal pain. Within 12-48 h of the onset of fever, purpura developed associated with vascular collapse and peripheral necrosis. All 10 children died. Cerebrospinal fluid examinations did not suggest meningitis and, when done, tests were negative for Neisseria meningitidis. Other culture, serological, and necropsy examinations did not reveal a cause. Case-finding uncovered another cluster of similar illness in children in a second town and sporadic cases in five other cities. Two case-control studies demonstrated that children who became ill were significantly more likely than control children to have had conjunctivitis during the month before illness. This conjunctivitis was purulent, preceded the onset of more severe disease by 3-15 days, and had resolved before fever began. Although no conjunctival cultures were obtained from case-children, Haemophilus aegyptius was the most common pathogen isolated from other conjunctival cultures during the epidemic. This organism was also isolated from a non-aseptic skin scraping from 1 case child. A 25-megadalton plasmid distinguished the H aegyptius isolates epidemiologically associated with illness from other Brazilian conjunctival isolates. Brazilian purpuric fever is a newly recognized syndrome of epidemic purpura fulminans associated with antecedent purulent conjunctivitis, possibly caused by H aegyptius.