We provide evidence that olive pollen extract can induce asthmatic response. The pattern of airway response to olive pollen is investigated. Nineteen patients with seasonal allergic rhinitis and asthma, suspected to be due to olive pollen, all of whom had positive skin-prick test, were investigated. Bronchial challenge with olive pollen extract were performed and the peak flow rate was followed for 20 hr. Eight patients developed dual asthmatic response (DAR), six patients developed early asthmatic response (EAR) and five patients had no asthmatic response. The early maximal fall in FEVI and the PD15 were not different between the group with DAR and the group with EAR only. We conclude that olive pollen can induce dual asthmatic response.