ABSTRACT.We compared the use of a standard metered aerosol actuator with the tube spacer in delivering 500 micrograms of terbutaline sulphate to the airways of seven children with clinical asthma. Each child used the standard metered aerosol in his usual way and the tube spacer with a 5 second delay between actuation and inhalation on separate occasions. Response was measured by change in forced expiratory volume in one second (FEV1). We found no significant difference in bronchodilatation between the two methods of aerosol delivery. We conclude that the tube spacer is an effective way of delivering a metered aerosol and that it has the advantage of allowing up to 5 seconds between actuation and inhalation. The tube spacer has particular application in young children who have difficulty in co‐ordinating their inspiration with metered aerosol actuatio