An outbreak of serotype 1 Streptococcus pneumoniae infection involving both adults and children occurred in central Australia during the winter months of 1991. Eighteen patients, mainly Aboriginal men, presented with culture-positive serotype 1 bacteraemic pneumonia. In this group, 11 of 12 adults for whom medical records were available were alcohol dependent. Thirteen children who were separately studied were hospitalised with acute lower respiratory tract infection: none had bacteraemia but all had upper airway colonisation by type 1 pneumococci. Antibiotics taken by 8 of the 13 children before admission to hospital may have compromised the isolation of type 1 pneumococci from blood cultures. Since the availability of antibiotics, epidemic pneumococcal infection is infrequent and has not been reported in Australia. In three outbreaks of type 1 disease recorded elsewhere crowding and alcoholism were identified as contributory factors. In the 16 month period before this outbreak none of 162 strains of pneumococci isolated from blood (32 strains) and nasopharyngeal secretions (130 strains) from Aborigines with acute lower respiratory tract infection and meningitis in the Alice Springs region were serotype 1 organisms.