This review aims to give an updated overview of the worldwide situation of off-label and unlicensed drug use in the paediatric field, also taking into account the safety of this kind of treatment. A Medline and Embase search was performed between 1990 and 2006 and a total of 52 studies were identified and included in the systematic review. From the authors' analysis of the literature, the extent of paediatric unlicensed/off label use is higher in neonatal and paediatric intensive care units and oncology wards, compared with primary care. Moreover, among the nine studies reporting the contribution of an off-label/unlicensed drug use to the occurrence of adverse events, the percentage of unlicensed and/or off-label prescriptions involved in an adverse drug reaction ranged between 23 and 60%. To ensure that children are not exposed to unnecessary risks, controlled clinical trials are required. In addition, future research should be directed towards the identification of individual drugs that cause serious adverse drug reactions and lack product information.