An open multicenter randomized, cross over study has compared the patients acceptance and preference of nedocromil sodium delivered as metered dose inhaler (MDI) containing 112 puffs and attached to an open tube spacer, the Syncroner with the same product as MDI containing 56 puffs delivered through a standard mouthpiece adaptator. One hundred and forty four patients (67 males) suffering from moderate asthma (mean FEV1: 86%) aged 18 to 70 years received alternatively 2 puffs of 2 mg 4 times a day of nedocromil sodium either by Syncroner or by the standard adaptator for two weeks in random order. The acceptance of each device was assessed by a questionnaire after two weeks of treatment. At the end of the study, the preference was recorded globally by the mean of a visual analog scale and for each of the following criteria: tolerability, shape, efficacy, hygiene, easiness to use, cleaning, contents and confidence. After two weeks of treatment the Syncroner was as well accepted as the standard mouthpiece and even better in terms of contents, cleaning and confidence. At the end of the study, 50.4% of patients prefering the Syncroner and 49.6% the standard mouthpiece. Patients significantly favoured the Syncroner because of its contents, hygiene, and cleaning (p < 0.05 for these 3 criteria) and tolerability (p = 0.07). In conclusion, after two weeks of treatment, the Syncroner was as well accepted as the standard MDI, 50% of patients preferred the new inhalation device. Considering its interest as training aid and the better lung deposition, it can be proposed for drug delivery without risk of a rejection by patients.