Inhalation of on-demand salbutamol (ODS) several times daily is sometimes the only beta2-agonist prescribed in moderate persistent asthma, whereas a long-acting beta2-agonist should be added. This trial aimed to compare the efficacy of formoterol dry-powder capsule 12 microg b.i.d. (Foradil) and ODS in patients with moderate persistent asthma treated with inhaled corticosteroids, in the conditions of real practice. Two hundred and fifty-nine patients were randomized (formoterol; 130; ODS: 129) in this open, parallel-group trial. The mean increases in morning peak expiratory flow (PEF primary variable) and evening PEF over the 3-month treatment period were statistically significantly higher with formoterol: +25.7 and +24.1 l min(-1), respectively vs. +4.5 and +0.5 l min(-1) respectively with ODS. The increase in FEV1 was statistically significantly higher with formoterol at months 1 and 3. Formoterol reduced the use of salbutamol as rescue medication by two-thirds. The percentages of symptom-free days and nights statistically significantly increased with formoterol (+20% and +33% respectively), but did not significantly change with ODS. Clinically relevant and statistically significant improvement in the mean total score of the St George's Hospital Respiratory Questionnaire was observed in the formoterol group. Adverse events were similar in the two groups. The results show that treatment with formoterol has significant advantages over ODS in patients with moderate persistent asthma.