Aims To: (1) determine the effect of computer- and web-based interventions on improving eating behavior (e.g. increasing fruit and vegetable consumption; decreasing fat consumption) and/or diet-related physical outcomes (e.g. body mass index) among children and adolescents; and (2) examine what elements enhance success. Background Children and adolescents are the heaviest they have ever been. Excess weight can carry into adulthood and result in chronic health problems. Because of the capacity to reach large audiences of children and adolescents to promote healthy eating, computer- and web-based interventions hold promise for helping to curb this serious trend. However, evidence to support this approach is lacking. Design Systematic review using guidelines from the Cochrane Effective Practice and Organisation of Care Group. Data sources The following databases were searched for studies from 19982011: CINAHL; PubMed; Cochrane; PsycINFO; ERIC; and Proquest. Review methods Fifteen randomized controlled trials or quasi-experimental studies were analysed in a systematic review. Results Although a majority of interventions resulted in statistically significant positive changes in eating behavior and/or diet-related physical outcomes, interventions that included post intervention follow-up, ranging from 318 months, showed that changes were not maintained. Elements, such as conducting the intervention at school or using individually tailored feedback, may enhance success. Conclusion Computer- and web-based interventions can improve eating behavior and diet-related physical outcomes among children and adolescents, particularly when conducted in schools and individually tailored. These interventions can complement and support nursing efforts to give preventive care; however, maintenance efforts are recommended.