Background: The objective of this study was to provide national figures on the prevalence of breakfast-skipping and the association with sociodemographic variables in 4–15 year old children. Methods: Data of 4,377 children were collected. A food questionnaire (24 h recall) was completed by the parents or by the older children themselves. Results: Five percent of the children in primary school and 13% of the children in secondary school skipped breakfast before going to school. Breakfast-skipping is more frequent in girls, older children, children of fathers of low education or living with a single parent and in children attending school in a large city. Conclusions: The results of this study point out the need for preventive programmes to encourage breakfast consumption in certain groups at risk.