When a new holding chamber for administrating inhaled medication is to be marketed, it needs to be compared with existing chambers with two questions in mind: is this chamber well accepted by patients and is there an in vitro equivalence? We compared the new small volume non-electrostatic valved holding chamber, usable with all pressurized metered-dose inhalers and equipped with a funny facemask, Vortex (Pari GmbH, Germany), to the most frequently prescribed holding chamber in France, Babyhaler (GlaxoSmithKline Laboratories). Preferences were studied for 75 families with a child no more than 4 yr old, using standard questionnaires. An in vitro study assessed the delivered dose and the particle size distribution of two HFA beclomethasone dipropionate pressurized metered dose inhalers (Becotide 250 microg per dose and Nexxair 100 microg per dose) by dose uniformity sample apparatus and cascade impactor according to the European Pharmacopoeia. Vortex was preferred by 95% of the families because of its small size, its duck facemask, and its robust appearance. Among children able to give their opinion, 86% preferred Vortex to Babyhaler. In vitro, both holding chambers reduced the delivered dose of beclomethasone dipropionate and increased the quantity of particles smaller than 5 microm in diameter with both medications. A higher proportion of fine particles was obtained with Nexxair than with Becotide (p < 0.05) and with Vortex than with Babyhaler (p < 0.05). As expected, throat deposition is dramatically reduced for both drugs with both holding chambers. The in vitro difference in the particle size distribution of beclomethasone dipropionate with both holding chambers probably has no clinical influence.