In a matched group design, two groups of children suffering from a psychosomatic disease (bronchial asthma and ulcerative colitis) were compared with two groups of children suffering from other chronic illnesses affecting the same organ (cystic fibrosis and Crohn's disease) and with healthy subjects with regard to locus of control. With the exception of bronchial asthma, all clinical groups were characterized by greater internal locus of control. There were no significant relationships between the IE-dimension and further clinical parameters specific to each disease. Furthermore, there was an indication that psychiatric disturbance in general is related to external locus of control. The IE dimension did not contribute to a differentiation between the types of psychosomatic and chronic illness.