To elucidate the effect of oxitropium bromide (OTB), an anticholinergic drug, on dyspnea and gas exchange during exercise in patients with chronic obstructive pulmonary disease (COPD), we performed the cycle exercise test on 19 patients with COPD (mean age, 72.0 +/- 1.9 years; mean FEV1, 1.28 +/- 0.07 L) before and after inhalation of OTB, 300 micrograms, or placebo, 300 micrograms, in randomized fashion. Spirometry was performed immediately before and 30 min after inhalation of either OTB or placebo. Dyspnea during exercise was evaluated using the Borg scale (BS) and the slope of the regression between BS and oxygen uptake (VO2) during exercise (Borg scale slope: BSS). Arterial oxygen saturation (SaO2) was continuously monitored by pulse oximeter during and after exercise. We also measured the recovery time, which was defined as the time to recover decreases in SaO2 after exercise. After OTB, spirometric indices were improved (delta FEV1 16.8 +/- 0.9 percent) and maximal VO2 during exercise increased significantly (from 986 +/- 46 ml/min to 1,156 +/- 55 ml/min, p < 0.01), but not after placebo. The maximal scores of BS and the BSS were significantly decreased after OTB, but not after placebo. Although the SaO2 at rest and during exercise did not differ with or without either OTB or placebo, the recovery time after OTB (77.3 +/- 6.8 s) was significantly shorter than that before administration (98.4 +/- 14.6 s) (p < 0.01). We conclude that the inhaled OTB produces small but significant improvement both in dyspnea during exercise and in exercise performance in stable COPD and may contribute to improve the quality of life in some patients with COPD. However, gas exchange during exercise of COPD patients is little affected by OTB.