The persistent lack of information on the paediatric use of most medicinal products is a major hindrance towards an optimal treatment of paediatric patients. Several studies have documented the high prevalence of off-label use in paediatric population. No comprehensive studies, however, exist that analyse in full all prescriptions for all dispensed drugs, especially in view of the recent intervention by the European Medicine Agency to tackle this issue. We have assessed the drug prescription pattern in the paediatric outpatient population of Lombardy, which has a reliable record of such prescriptions focusing on off-label drug use. We analysed all dispensed outpatient prescriptions to children aged 0-18 years and the proportion of off-label drug use in 2011, using data from the regional administrative prescriptions database. A total of 4,027,119 prescriptions were dispensed, of which 133,619 (3.3 %) were off-label. The anatomical therapeutic chemical classes most involved in off-label prescriptions were antibiotics for systemic use (33,629), alimentary tract and metabolism (31,739) and respiratory tract (31,458). The highest rate (8 %) of off-label drug prescriptions was observed in the age range 0-1. The study revealed also an inappropriate prescription pattern for fluoroquinolones and drugs targeting the cardiovascular and musculoskeletal systems. We identified inappropriate prescriptions for specific drug classes, highlighting the need of increasing pharmacological studies in the paediatric patients and specific critical drugs/drug classes in which such studies are particularly urgent. Depending on the region, inappropriate paediatric drug prescriptions may affect different drug classes, indicating the need of tailoring specific programmes of information.