The steroid-sparing capacity of methotrexate in asthmatics is still being debated. The present study was undertaken to evaluate the effect of low-dose methotrexate on steroid consumption in patients with severe asthma, who require very high doses of systemic corticosteroids. We conducted a randomized, double-blind, parallel clinical trial in 24 patients with long-standing asthma. After a 3-week run-in period, patients received a 16week course of either 15 mg of oral methotrexate weekly or matched placebo in addition to their previous asthma therapy. The daily steroid dose (at run-in 30 -+ 14 mg/day in the methotrexate group; 25 -+ 9 rag/day in the placebo group (NS)) decreased by 24% in the methotrexate group (p < 0.01) and by 5% in the placebo group (NS) during weeks 9-16 of the treatment period when compared with run-in values. However, there was no difference in steroid consumption between the two groups at any time. We conclude that in patients with severe asthma who require very high doses of systemic corticosteroids, short-term treatment with methotrexate allows only a marginal steroid reduction. Our study does not support the use of methotrexate as a steroid-sparing agent in asthmatics.