Objective: To determine the effectiveness of a psycho-educational group intervention for chronically ill children. Methods: Based on principles from cognitive behavior therapy and information from previous research about children's experiences with coping with a chronic disease we developed an intervention to be used for children with different chronic diseases. The program, called Op Koers (OK), with six sessions for different age groups, was evaluated by standardised and researcher-developed psychological measures. Results: A total of 109 patients participated in the study on the effects of the psycho-educational intervention. Improvements in behavioral-emotional outcomes, social competence, information seeking, relaxation and positive thinking were found both in short and medium term. Additionally, the sessions received positive appraisals. Conclusions: The program appears to have a significant and positive impact on chronically children. Further research is needed to establish the effects of the intervention. Practice implications: Beneficial effects can be expected from the implementation of a psycho-educational group intervention for children with heterogeneous chronic health conditions. © 2006 Elsevier Ireland Ltd. All rights reserved.