In the present investigation the effect of fenoterol powder for inhalation has been compared to that of fenoterol spray in 20 adult patients with reversible obstructive lung disease. No difference could be demonstrated between the two forms of the drug in a randomized cross-over study. Neither was it possible to demonstrate any difference between the two preparations following the use of the drug at home over a minimum of four days, with regard to daily PEF registration and symptom scores. Nine of the patients preferred spray, six powder.