Nedocromil and salbutamol are effective drugs in preventing exercise-induced asthma (EIA). The aim of this study was to compare the protective effects of both drugs and a combination of both drugs against cold dry air-induced bronchoconstriction, using cold dry air challenges (CACh) as a surrogate for exercise. Twenty-five atopic children (mean age 13.7, range 8-18 yrs) with EIA participated in the study. Lung function tests were performed before medication, 30 min after medication and just before CACh, and 3 and 15 min after the challenge on four consecutive days. CACh consisted of a 4-min isocapnic hyperpnoea of -10 degrees C, absolutely dry air. Treatment consisted of nedocromil (two puffs of 2 mg) plus placebo, salbutamol (two puffs of 100 microg) plus placebo, the combination of both drugs, and placebo alone, in a random order. Both active drugs were significantly more protective than placebo and the combination showed an additive effect. Mean maximum postchallenge decrease in forced expiratory volume in one second after placebo was 27+/-8.1%, 12+/-9.5% after nedocromil, 8+/-10.4% after salbutamol, and 4.5+/-6.71% after the combination of both drugs, respectively. These results suggest that both drugs protect against exercise-induced asthma. Although not as effective as salbutamol and combined medication, nedocromil can give sufficient protection for many patients.