Fenoterol hydrobromide (Berotec; formerly Th 1165a) is a sympathomimetic bronchodilator drug. Twenty subjects with mild to moderate reversible bronchospasm completed a double-blind multiple crossover study of single doses of 5 mg, 7.5 mg, and 10 mg of fenoterol hydrobromide, 24 mg of ephedrine, and placebo. Spirometric and body-plethysmographic measurements were performed sequentially prior to administration of drug or placebo and each hour up to eight hours afterwards. No significant drug-response relationship was noted for pulse rate or blood pressures, and side effects (eg, shakiness, nervousness) were minimal. Administration of fenoterol resulted in bronchodilation; a peak effect was noted at two to three hours after administration, and the duration of action was up to eight hours. A statistically significant dose-response relationship was observed; therapy with 5 mg of fenoterol hydrobromide was superior to placebo and equal to ephedrine, and doses of 7.5 mg and 10 mg of fenoterol hydrobromide were significantly better than placebo or ephedrine.