The objective of our article is to survey the prevalence of overweight and obesity among 6- and 9-year-old children in Emilia-Romagna, a region of Central-North Italy, and to study the eating habits and behaviours of these children and their families. During 2003 and 2005, we analysed a stratified sample of the general population of children attending pre-school (2681 children aged 6 years) and primary school (2955 children aged 9 years). Their height and weight were measured by healthcare workers. In the 6-year-old children, information concerning their eating habits was collected by means of a questionnaire completed by their parents. The prevalence of overweight was 16.5% in 6-year-old children and 20.6% in 9-year-old children. The increase of overweight from 6- to 9-year-old children was observed in males (13.5% in 6-year-old/21.3% in 9-year-old boys), but not in females. The prevalence of obesity was 8.9% in children aged 6 years and 9.0% in those aged 9 years, and it was higher in comparison with Italian surveys carried out in 1993 and in 2001: 7.5% in 6-year-old and 7.8% in 9-year-old children in 1993, and 6.6% in 6-year-old and 7.2% in 9-year-old children in 2001. In pre-school children, overweight and obesity were closely influenced by the education level, occupation and nutritional status of the parents.