We describe a subject who experienced a nonimmediate asthmatic reaction without airway hyperresponsiveness prior to the exposure or on repeated measurements, 90 min and 24 h after exposure. There was a major increase in sputum eosinophilia: 3% of cells obtained at baseline, 19% 90 min after exposure and 42% 24 h after exposure. We have demonstrated that a nonimmediate asthmatic reaction can occur without an increase in airway hyperresponsiveness despite a clear increase in eosinophilic airway inflammation.