We studied the steroid-sparing effect of dapsone in 10 subjects with chronic asthma in a preliminary open trial. Dapsone was chosen because it inhibits neutrophil function and possesses anti-inflammatory effects in a variety of disorders. The study group consisted of 10 subjects with stable, steroid-dependent asthma, aged 23 to 80 years, with normal glucose-6-phosphate dehydrogenase levels. Average daily baseline prednisone dose ranged from 5 to 60 mg. Dapsone, 100 mg, twice daily, by mouth, was started after a 1-month baseline period. Baseline steroid dose, symptom scores, and daily peak flow rates were compared to the latest available 4-week period of dapsone treatment. Average cumulative monthly prednisone dose was reduced from 428 mg to 82 mg (p less than 0.02). Five of 10 patients stopped steroids by month 6 and two additional patients by month 13. Two additional patients demonstrated a coincidental 74% reduction in steroid dose, and one patient demonstrated no response. Clinical parameters remained stable despite steroid reduction. These preliminary data suggest dapsone may have steroid-sparing effects in chronic asthma.