We used cyclosporin to treat 12 adult patients with severe bronchial asthma who had been on systemic steroids for an average of 16 years. During the baseline period, lasting 4-6 months, therapy with high doses of inhaled beclamethasone, aminophylline and salbutamol was standardized and a minimum necessary dose of systemic steroids was established. After 9 months' treatment with low-dose cyclosporin (average whole-blood trough levels of 105 ng/ml), in six patients the daily dose of oral prednisone could be reduced from mean 30 mg to mean 11 mg, while daily symptom scores and peak expiratory flows improved significantly. This was accompanied by a reduction in exacerbations of asthma. However, in six other patients attempts to taper the steroid doses were unsuccessful, and cyclosporin was stopped after 4 to 7 months. These preliminary results suggest that cyclosporin might be of benefit in some patients with steroid-dependent asthma.