A randomly selected group of 50 New Zealand wood workers was studied. The level of airborne wood dust to which they were exposed ranged from 1.0-24.5 mg/m3. The wood workers reported experiencing higher rates of both lower and upper respiratory tract symptoms than a control group of office workers. Inhaled wood dust, in particular from rimu (Dacrydium cupressinum), was frequently cited by workers as being associated with respiratory tract symptoms. The wood workers' responses to the respiratory symptom questionnaire, and serial recordings of peak expiratory flow rate were used to screen the group for suspected cases of occupational asthma. Five cases fulfilled the study's criteria for suspected occupational asthma. In four of these, further evidence was found to support this diagnosis. We conclude that exposure to wood dust may cause occupational asthma in the woodworking industry in New Zealand.