The common clinical assumption that stress has a deleterious effect on metabolic control in insulin dependent diabetes mellitus (IDDM) has not been confirmed in children and adolescents. This cross sectional study of 43 children and adolescents with IDDM and their families examined the relations between family life stress, family social support, and metabolic control. High family life stress was found to be strongly correlated with HbA1c in the whole group (n = 43) and in children under 12 years (n = 27) when considered separately. Family social support was not found to be directly related to HbA1c, but was found to buffer the effects of family life stress. These findings support the hypotheses that family stress affects metabolic control in IDDM and that good social support buffers these deleterious effects.