Increasing dose of budesonide, each dose given for a minimum of 1 month, were administered via a Nebuhaler to 14 patients. Two consecutive abnormally low fasting morning plasma cortisol values, taken 2 weeks apart, were accepted as evidence of hypothalamo-pituitary-adrenal (HPA) hypofunction. Data from nine of the 14 patients entering the study were available for analysis. One patient developed HPA hypofunction while inhaling 2.4 mg budesonide per day and another retained normal HPA function on a dose of 12 mg. In the remaining patients, intermediate doses resulted in suppression, or the patients were withdrawn unsuppressed for other reasons (n = 3). The results in this small patient sample suggest that budesonide administered via the Nebuhaler in doses up to 1.6 mg daily does not significantly affect plasma cortisol.