A total of 102 patients had their asthma treatment with beclomethasone dipropionate (BDP) optimized in order to achieve the best possible control of symptoms. Thereafter, the BDP doses were gradually reduced over a 2-year period (1988–90) to the lowest possible without deterioration of their asthmatic condition. In the beginning of 1990, treatment was changed in 76 patients (group A) to the nearest possible dose of budesonide delivered via Turbuhaler® Twenty-six randomly selected patients (25% of the study population; group B) continued treatment with BDP. In both groups, dose reductions were tried during 1990–2 every third month as long as the patients remained symptom-free and without significant decreases in FEV1 or PEF. In group A, the maintenance dose could be reduced from 1003.9 ± 325.4 μg BDP (mean ± SD) to 602.9 ± 454.4 μg budesonide Turbuhaler (P<0.001). In group B, no significant dose reduction was possible; the mean dose was ± SD 1067.3 ± 36.6 μg in 1990, and 1019.2 ± 324.7 μg in 1992. The results indicate that, in efficacy, 0.6 mg budesonide Turbuhaler corresponds to approximately 1.0 mg BDP with volumatic spacer. This difference is probably due to an improved pulmonary delivery of budesonide with Turbuhaler.