Forty seven children (6-14 years), with an acute mild or moderate attack of asthma (clinical score 3 or FEV1 > 50% of the predicted), were treated with terbutaline sulphate, by inhalation route with a dry powder inhaler (Turbuhaler - 0,5 mg - group T; N=27, or by a nebulizer 1% solution-in saline-compressed air (6 l/min.) group S; N=20. The children were evaluated at 5, 15, 25 and 30 minutes after the initial treatment. In both groups a significant fall of the clinical score (starting at 15 minutes) (p < 0.05) and a significant improvement of the FEV(1), VC and FEF25-75% (starting at 5 minutes), were observed (p < 0.05). There were no significant changes in heart rates, respiratory rates and blood pressure (p > 0.05). At the end of the first treatment, the number of patients with a FEV(1) < 80% was similar in both groups (T = 13/27 and S = 10/20). The same treatment was repeated, and all the children showed a marked improvement, except for one boy of the group T was hospitalized. In conclusion, children with mild or moderate acute attacks of asthma can be treated up to a week with an inhalation of dry powder, resulting in adequate bronchodilatation without important side effects.