Twenty-four patients with severe steroid-dependent asthma participated in a double-blind cross-over study performed in two centers. After a run-in period of 2 weeks when beclomethasone dipropionate (BDP) (400 micrograms/day) was used, the patients were treated for 4 weeks with either a high-dose (1600 micrograms/day) or a low-dose (400 micrograms/day) of budesonide (Pulmicort). Thereafter the doses of budesonide were switched and the treatment continued for a further 4-week period. Patients treated with high-dose budesonide displayed significant improvements in airway functions. In addition, subjective scores for cough, sputum production and dyspnoea were more improved in the high-dose group than in the low-dose group. The need for concomitant beta 2-agonist therapy was also significantly reduced during the high-dose treatment. No significant changes in plasma cortisol levels were detected and no adverse effects of importance were registered. The results indicate that high-dose budesonide treatment improves the clinical status of patients with severe steroid-dependent asthma more than a low-dose therapy but without causing systemic side-effects.