Comparative examinations were performed on each N = 36 subjects, with bronchial asthma, cystic fibrosis and healthy controls, with regard to individual psychopathology, family functioning, and the relationship of clinical parameters to psychopathology. Children suffering from cystic fibrosis had the highest prevalence rate of psychiatric disorder. Findings of the psychiatric assessment in general were cross-validated by parent's and teacher's questionnaires. Data relating to family function were less differentiating between the groups. In both groups of diseases significant correlations between clinical parameters and psychopathology were detected.