If we assume that the only function of a spacer is that to facilitate the esecution of a spray, its use is limited to small children who do not collaborate (below age 6-7 years). However, spacers seem to improve the effectiveness of drugs and reduce both directly and indirectly the side effects. The assess if these characteristics have a role in clinical practice, the response to 100 micrograms of salbutamol administered directly by Autohaler was compared to that obtained with the same dose administered with three different spacers, Aerochamber, Babyhaler, Volumatic. A series of 88 asthmatic subjects with a FEF 25-75 less than 70% of the predicted value was considered. Overall patients provided 118 responses to the bronchodilator: 17 using the Aerotec (Autohaler), 38 the Aerochamber, 33 the Babyhaler, 30 the Volumatic. The response was evaluated considering the parameters obtained by spirometry just before, 5 and 20 minutes after the inhalation of salbutamol. Heart rate was also measured at the same time points. Heart rate, but not spirometric parameter were increased by the use of the Autohaler, proving that the drug had been inhaled. All the spacers determined a significant increase in the parameters considered. No significant difference was detected among spacers, although the smallest (Aerochamber, Babyhaler) showed a trend to a better response, in particular before age 7 years. The complete ineffectiveness of direct inhalation and the excellent response to inhalation with spacers show the indispensability of the latter, independent of age. Although no substantial difference among spacers was detected, the trend to obtain a better response with smaller spacers inclines us to use them in particular between 4 and 7 years of age. The negative correlation between the increase in spirometric parameters and the age of the patient would allow to have doses aimed to age or to body weight.