We present a systematic review of the effectiveness of vaccinating healthy children to protect others. Primary studies were identified by searching standard electronic databases, internet sites, trials registers and citation lists to January 2004 and subjected to critical appraisal. Eight randomised controlled trials, three community studies and three economic evaluations met the inclusion criteria. The evidence suggests that vaccinating healthy children against influenza has the potential for reducing the impact of influenza epidemics. However, further evidence is needed as limitations of study design or execution mean that the community benefits are difficult to quantify.