The rise in childhood overweight and obesity in less developed countries and those with transitional economies is widely recorded. In many cases, this increase in overweight is occurring in societies where levels of under-nutrition remain high. Overweight particularly affects children in affluent families and urban families and is usually much less in rural areas. Changes such as the availability of more Western-style foods, the prevalence of snacking, a decline in physical activity, less sleep and the inactivity associated with watching television may all be contributing to the rise of overweight. The complications of overweight/obesity are already being seen in some affected children. Efforts to treat and prevent overweight in children are needed urgently if the appalling levels of overweight currently seen in the well established market economies of Europe and North America are to be avoided by less developed and transitional economies.