Obesity prevention is necessary to address the steady rise in the prevalence of obesity. Although all experts agree that obesity prevention has high priority there is almost no research in this area. There is also no structured framework for obesity prevention. The effectiveness of different intervention strategies is not well documented. Regarding universal prevention little rigorous evaluation has been carried out in larger populations. Obesity prevention has been integrated into community-wide programmes preventing coronary heart disease. Although effective with respect to reduction in cardiovascular risk factors these programmes did not affect mean body mass index (BMI) of the target populations. Selective prevention directed at high risk individuals (e.g. at children with obese parents) exhibited various degrees of effectiveness. However, at present, definitive statements cannot be made because of the limited number of studies as well as limits in study design. Finally, targeted prevention produced promising results in obese children when compared to no treatment. However, there are only very few longterm follow-up data. There is no clear idea about comprehensive interventions studying combinations of different strategies. It is tempting to speculate that predictors of treatment outcome (e.g. psychological and sociodemographic factors) may also serve as barriers to preventive strategies, but this has not yet been investigated. Taken together, obesity prevention should become a high priority research goal. First results of obesity prevention programmes are promising. As well as health promotion and counselling, better school education and social support appear to be promising strategies for future interventions.