In this cross-sectional study the age-dependency of coping behaviours of 43 children and adolescents with IDDM aged 8 to 18 years has been assessed by means of the German version of the Kidcope (Rathner u. Zangerle 1996). Everyday stressors as well as disease-related stressors were used. Significant age-dependent differences in the frequency of coping behaviours could be found in all strategies except self-criticism. Especially distraction and wishful thinking were significantly more often used by children than by adolescents, whereas adolescent used significantly more often resignation. The more frequent use of resignation by adolescents is not due to a longer duration of illness, but to their developmental stage. Thus, in chronically ill children and adolescents developmental aspects showed a stronger influence on coping than duration of illness. Self-criticism, blaming of others and social withdrawal are as rarely used by children as by adolescents. Self-rated efficacy of coping strategies showed almost no age differences; social support was rated as the most efficient coping strategy by both age groups. Resignation, in the sense of a cognitive acceptance of the illness, seems to be more efficient for adolescents than for children. It is concluded that the developmental process of children and adolescents with chronic illnesses such as IDDM may lead to a better cognitive acceptance of the disease.