Fourteen out-patients with chronic bronchitis (n = 5) or chronic bronchial asthma (n = 9) entered a trial devised to evaluate the effect of the combined inhalation by pressurized aerosol of fenoterol 200 micrograms + ipratropium bromide 80 micrograms three times daily in a 12-week period of treatment. On the basis of the ventilatory and clinical findings, effective bronchodilatation with clinical improvement after drug inhalation was noticed throughout the whole observation time. In detail, the behaviour either of the FEV1 values at the control days or of the daily self-monitored peak expiratory flow (PEF) data showed a constant, statistically significant increase in the post-bronchodilator values with a prompt, long-lasting and persistent effect over the 3-month period; self-monitored PEF rates were particularly consistent with this result. No side-effects were seen in any cases, including the 5 patients who needed extra use of inhalers. The findings of the trial suggest that the combined inhalation of fenoterol and ipratropium bromide may play an important role in long-term therapy of many patients with chronic bronchitis or chronic bronchial asthma.