Three cases of pyogenic Haemophilus influenzae meningitis in adults have been diagnosed within the Brisbane Metropolitan area in the last twelve months. This had been considered a very unusual cause of meningitis in adults which has not previously been recorded in the Australian literature, and should alert clinicians to a possible alteration in the age specificity of this disease. Two of the three isolates proved resistant to ampicillin; this emphasizes the need to exclude beta lactamase production in all Haemophilus isolates from critical infections. All three patients recovered without significant sequelae but the choice of primary antimicrobial in adult meningitis remains open to question.