Ten children with mild bronchial asthma underwent bronchial challenge with carbachol on three consecutive days; using a double-blind technique, they were given inhaled saline placebo on the first day and placebo or sodium cromoglycate (SCG) on the second and third days 15 min prior to the bronchial provocation test with carbachol. We did not find any significant difference between the baseline and placebo values, but we did obtain a statistically significant difference when comparing baseline with post-SCG and placebo with post-SCG values. These results demonstrate a protective effect of SCG on carbachol-induced bronchospasm in asthmatic children.