We present the case of a 20-month-old child who required admission to the intensive care with a presumptive diagnosis of acute laryngo-tracheo-bronchitis, for the management of acute upper airway obstruction. This child had received a complete course of Haemophilus influenzae type B (Hib) vaccine. Subsequent events showed that the diagnosis was not laryngo-tracheo-bronchitis but acute epiglottitis. We propose that a full course of vaccination is no guarantee against a subsequent illness with Hib and may actually lead to the wrong diagnosis and possibly life-threatening consequences.