BACKGROUND : The incidence and prevalence of childhood chronic disease is increasing worldwide. Obesity, poor diet and lifestyle may be more prevalent in children with a chronic disease than in their healthier contemporaries. The Growing Up in Ireland (GUI) study is a nationally representative cohort study of children living in the Republic of Ireland. The study has collected information from 8568 9-year-old Irish children on their experiences within their families, childcare settings, schools and communities, and how these impact on all aspects of children's development. OBJECTIVE : This study aims to establish the prevalence of parentally reported chronic disease in children in Ireland and to describe their diet and lifestyle. METHODS : This study analyzed data from the Growing Up in Ireland longitudinal child cohort study and compared the diet, lifestyle and prevalence of obesity in children with and without a parentally reported chronic disease. RESULTS : Overall, 954 parents in the sample (11.1%) reported that their child had a chronic illness and 43.4% of these children are hampered by it in their daily activities. Respiratory disorders were the commonest type of chronic disease (46%) reported. Children with a chronic illness were more likely to be overweight or obese (32.9% compared to 25.0% of those without a chronic illness, p < 0.001). Children with chronic illness were also found to have a poorer diet, take less exercise and experienced significantly more social isolation than their peers (all p < 0.05). CONCLUSIONS : Public health measures to address diet and lifestyle choices need to be cognisant of the needs of children with chronic diseases and tailor activities offered to be inclusive of all children. Medical professionals having contact with children with chronic conditions need to remember to reinforce the importance of diet and lifestyle whenever possible and to explore with families solutions to barriers to making healthy diet and lifestyle choices.