Fenoterol hydrobromide (200 micrograms), ipratropium bromide (40 micrograms) and a combination of the two in the same dosage were administered by metered dose inhaler on 3 separate days to 20 patients with chronic bronchitis and emphysema. On each day, baseline forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFR) and mid maximum flow rate (MMFR) were recorded. The values were again recorded after administration of the drug at 15, 30, 45 and 60 minutes. Side effects if any were recorded. There was a significant increase from baseline in FVC and FEV1 with all the three regimens at 15, 30 and 45 minutes. However, the rise in MMFR was significant only with ipratropium bromide and the combination regimen. At 60 minutes, the rise in FVC, FEV1 and MMFR was significant only with the combination regimen. There was no significant change in the PEFR values at any time with any drug. The difference in rise in all the four parameters with the 3 regimens was not statistically significant. No side effects were noted. Thus, a combination fenoterol and ipratropium bromide produced a more prolonged bronchodilatation, and ipratropium bromide perhaps acts both in the major (indicated by rise in FEV1) and small airways (measured by MMFR).