Chronic illness may be a risk factor for low self-esteem; however, previous meta-analyses are inconclusive whether children with a chronic illness have lower self-esteem than their healthy peers. The goal of the present study was to summarize available research in order to compare the self-esteem of children and adolescents with a chronic illness with that of healthy children. Random-effects meta-analysis was used to integrate the results of 621 empirical studies that compare levels of self-esteem of children with a chronic physical illness with healthy peers or general test norms. Studies were identified via the electronic databases Adolesc, Embase, Google Scholar, MEDLINE, PSNYDEX, PSYCINFO, and cross-referencing. Children with chronic illnesses have lower self-esteem than healthy peers or test norms (g=−0.18 standard deviation units). The lowest levels of self-esteem were observed in children with chronic fatigue syndrome and chronic headaches. Lower levels of self-esteem in children with a chronic illness were found in girls than in boys, in adolescents than in children, in children from developing or threshold countries, when results were collected from observer ratings rather than child reports, in studies published in the 1990s, and when children with chronic illnesses were directly compared with healthy children instead of test norms. Paediatricians, parents, and teachers should promote experiences of success and positive peer-relations, which are important sources of self-esteem. In addition, psychosocial interventions for children with chronic illnesses should be offered for children with reduced self-esteem.