BACKGROUND: The potential risk of adverse drug reactions (ADRs) in the paediatric population has become a public health concern and regulatory agencies in Europe and the US have acknowledged that there is a need for more research in this area. Spontaneous reporting systems can provide important new information about ADRs. OBJECTIVE: To characterize ADRs in children reported in Denmark over a period of one decade. METHODS: We analysed ADRs reported to the Danish Medicines Agency from 1998 to 2007 for individuals aged from birth to 17 years. Data were analysed with respect to time, age and sex, category of ADR (System Organ Class [SOC]), seriousness, suspected medicines (level 2 of the Anatomical Therapeutic Chemical [ATC] Classification System) and type of reporter. RESULTS: 2437 ADR reports corresponding to 4500 ADRs were analysed. On average, 234 ADR reports were submitted annually, corresponding to approximately two ADRs per report. From 2003 to 2005, an increasing number of ADRs submitted per report were observed, but after 2005 the reporting rate decreased. One-half of ADRs were reported for infants from birth to 2 years of age. Similar total numbers of ADRs were reported for boys and girls. The majority of ADRs reported were from the following SOCs: general disorders and administration site conditions (31%), skin and subcutaneous tissue disorders (18%) and nervous system disorders (15%). Reports encompassed medicines from ATC group J: vaccines and anti-infectives for systemic use (65%); and ATC group N: nervous system (17%). On average, 42% of ADRs were classified as serious. ATC group N had the highest proportion of ADRs that were classified as serious. Although physicians reported approximately 90% of the ADRs, a relatively large proportion of serious ADRs were reported by other sources. CONCLUSION: In Denmark, the ADR reporting rate in the paediatric population has declined since 2005. The majority of ADRs reported in young children were reported for vaccines and anti-infectives, but also a high number of serious ADRs were reported for medicines from ATC group N. The Danish Medicines Agency should monitor prescribing patterns more tightly to identify potential risks in the paediatric population in relation to the evolving pattern of medicine use among children.