Influenza virus is a major cause of respiratory illness in children, who have the highest attack rates of all age groups; furthermore, children are a main virus transmitter and contribute significantly to the spread of the disease. The impact of influenza on children is often underestimated but the mortality rate can be high. During the 2003–4 influenza season, there were 153 influenza-associated deaths among children in the US; of these, nearly 50% were previously healthy. Influenza is also an important cause of hospitalisation among those under 2 years of age, with a hospitalisation risk similar to that for the elderly and other high-risk groups. In addition, influenza frequently predisposes children under 3 years of age to complications such as acute otitis media and pneumonia. Influenza may also have substantial socioeconomic consequences for household contacts of children, largely related to parental productivity loss. The significant impact of influenza on children calls for effective prevention and management of this illness. Influenza vaccination of young children is currently recommended in the US and Canada, but few European countries have adopted similar policies. Lack of appreciation of the severity of influenza in children is still one of the greatest obstacles for widespread vaccination, but another major concern surrounds the cost-effectiveness of such an intervention. The future challenge to encourage vaccine acceptance is to increase awareness of the impact of influenza in children among both healthcare personnel and parents. There is also a clear need for new influenza vaccines that are even more immunogenic in young children.