The anticholinergic drug ipratropium bromide (Atrovent) can be described as having pharmacologically a high degree of activity and a certain bronchoselectivity when administered intravenously. Inhalation studies, however, indicate that this is the most suitable route of administration. Inhalation provides with small doses the most effective concentration locally at the smooth muscle of the airways without producing anticholinergic side effects due to absorption from the airways or from the gastrointestinal tract. In certain experimental models of allergic asthma, ipratropium bromide was shown to be capable of influencing favourably bronchoconstriction and mediator release. Extensive toxicological examinations revealed with high doses all typical symptoms of overdosing an anticholinergic drug, like mydriasis, dryness of the mucosae and meteorism with coprostasis. Acute and long term inhalation studies gave no evidence for a functional and morphological impairment of the lungs and airways.