Spacing devices have been widely advocated for asthmatic patients having difficulty actuating metered aerosols and co-ordinating inspiration. Studies have generally supported the slow inspiration/breath hold technique. This requires conscious respiratory control. Such control is often not possible in young children; consequently panting techniques are widely recommended. The panting technique has not been studied. The aim of this study was to compare the bronchodilator effectiveness of panting and the single breath maneuver, each followed by a breath hold, and each at functional residual capacity (FRC), using a Volumatic Space. The study design was a randomly allocated cross-over assessment of bronchodilator response for each technique. The drug dosage was controlled by limiting the inspired volumes of gas (single and cumulative) to the pretested inspiratory capacity. Two hundred micrograms of salbutamol was delivered into the spacer. Twenty-one patients were entered in the study and 15 (mean age +/- SD = 10.9 +/- 3.3 years) completed the protocol. There was no significant difference in bronchodilator response between the two groups. We conclude that the panting and the single breath techniques are equally effective in children of this age group.