To estimate the prevalence and evaluate the appropriateness of anti-asthmatic drug prescriptions in an Italian paediatric population, drug prescriptions involving 24,407 children <18 years old, dispensed during 2003 by the retail pharmacies of the local health unit in Lecco, Italy, were analysed. Children > or = 6 years old receiving anti-asthmatics were categorized into three subgroups based on the number of boxes prescribed: occasional (one box), low (two and three boxes) and high (> or = four boxes) users. A logistic regression analysis was performed to estimate the relationship between the drug use patterns and formulations, antibiotic co-prescriptions, systemic steroid prescriptions and rate of hospitalization. Anti-asthmatic drugs were prescribed to 6594 (12%) children and adolescents; 58% of whom received only one box of the drug. Prevalence varied according to age, with the highest values at 1 and 4 years (24% and 21% respectively), and decreased to 6% in 17-year-old adolescents. Inhaled steroids were the most prescribed drugs (83%). The most common of these was beclomethasone. Occasional, low and high users represented 58%, 29%, and 13%, respectively, of the treated population > or = 6 years old. High users were found to be at increased risk of systemic steroid prescriptions (OR 8.6) and hospital admission for asthma (OR 6.8). This study confirms that in Italy the prevalence of anti-asthmatic prescription is much higher than prevalence of disease, indicating that anti-asthmatics are over-prescribed. Moreover, steroids, especially nebulized, are mainly prescribed only once in a year, supporting the idea that are prescribed not for asthma, which as chronic disease requires a chronic therapy. The approach to create subgroups on the basis of number of boxes prescribed seems to be effective in estimating asthma severity and appropriateness of the therapies.