Health related quality of life (QoL) is a relevant criterion to understand well-being and function in children with chronic health conditions. Approaches to assessing quality of life are presented, based on a revision of the German KINDL questionnaire in the course of rehabilitation in three groups of chronically ill children (with diagnosis of asthma, atopic dermatitis or obesity), aged 8 to 17 years. Psychosocial and sociodemographic characteristics prior to, at the end and 12 months after rehabilitation were also assessed. At baseline, gender-, age- and diagnosis-specific impairments in QoL were found. Over time children improved, most clearly in children with obesity. Psychosocial predictors of QoL one year after rehabilitation were identified. The study shows that QoL assessment in children with chronic conditions is feasible and that children profit from rehabilitation programs. To further assess the QoL benefit in paediatric rehabilitation more studies are needed.