An 18-year-old man who worked in a furniture factory reported rhinitis and asthma when he was exposed to ash wood dust. Monitoring of the patient's peak expiratory flow rate (PEFR) when off work and at work showed increased variations of PEFR at work. Basal PC20 methacholine was 1.41 mg/ml. A bronchial provocation test (BPT) with a 1:1000 w/v ash wood dust extract induced a dual asthmatic response with a 7.5-fold increase of nonspecific bronchial responsiveness. Intradermal testing with ash wood extract elicited a positive immediate response. IgE antibodies against ash wood were found in the patient's serum with a RAST value of 0.57 PRU/ ml. Similar skin tests, BPT, and RAST with ash wood dust performed in control patients were all negative. All the studies performed suggest that our patient had occupational rhinitis and asthma caused by exposure to ash wood dust in which a type I immunologic mechanism was implicated.