OBJECTIVE: To determine whether day-care attendance was a risk factor for Haemophilus influenzae type b (Hib) disease, particularly for epiglottitis. METHODOLOGY: A case-control analysis of risk factors for invasive Hib disease was performed in Victoria, Australia between February 1988 and February 1990 prior to the introduction of immunization for Hib. A total of 210 cases and 367 day surgery hospital controls were enrolled prospectively. Data were collected by questionnaire at the time of admission. RESULTS: Logistic regression analysis showed that risk factors for meningitis were day-care attendance, household crowding and recent illness in a sibling. Risk factors for epiglottitis were day-care attendance and mother's birthplace in Australia or New Zealand. CONCLUSIONS: This study confirms that day-care attendance is a risk factor for Hib epiglottitis as well as meningitis. In addition, the mother's birthplace in Australia or New Zealand is a risk factor for epiglottitis in these data. The reason for this latter observation is unclear.