The aims of this study were to determine the characteristics and perceived levels of fatigue and the prevalence of depression in children with chronic fatigue syndrome and to assess the effects of illness on schooling and social functioning. Twelve children with chronic fatigue syndrome were compared with a matched group of children with cystic fibrosis and matched healthy controls. Levels of fatigue (fatigue questionnaire), depression (children's depression inventory), and social adjustment (semistructured interview with parents) were compared between groups. Children with chronic fatigue syndrome had significantly higher median scores for physical and mental fatigue and depressive symptomatology than either comparison group and five children scored as depressed on the children's depression inventory. Schooling and social functioning were seriously disrupted. Children with chronic fatigue syndrome reported high levels of fatigue affecting both physical and mental functioning, the association with depression found in adult studies was confirmed, and social adjustment was poor.