Responses of isolated human airways, obtained from a single asthmatic patient at thoracotomy, were compared to responses of airways from 10 non-asthmatic subjects in vitro. Asthmatic bronchiolar strips exhibited increased contractile responses to histamine, methacholine and leukotriene (LT) C4, and relaxed normally in response to 1-isoprenaline and forskolin. The non-adrenergic inhibitory response to field stimulation was low, but was not significantly different from control values. These results suggest that increased airway smooth muscle contractility may contribute to the asthmatic airways hyperresponsiveness in this patient.