Guinea-pigs were sensitized with killed Bordetella pertussis (3.85 X 10(11) cells . kg-1). The presence of the immediate type of immune response was verified by passive cutaneous anaphylaxis (PCA). In anaesthetized spontaneously-breathing guinea-pigs respiration rate, tidal volume, minute ventilation, dynamic lung resistance and dynamic lung elastance were estimated on the basis of airflow velocity and pressure in the oesophagus. After provocation by a single intravenous injection of the killed cells, respiratory frequency, elastance and resistance increased but tidal volume decreased. The preventive effects of aminophylline and clemastine (50 microns . kg-1, i.v.) were observed. B. pertussis not only alters adrenergic function but provocation in B. pertussis-sensitized guinea-pigs seems to be a good model for bronchial asthma.