In an exploratory study, the influence of severity of illness and coping style was examined in 86 children and adolescents with severe chronic renal failure. Psychological outcome was measured using the Strengths and Difficulties Questionnaire and The Harter Self-Perception Profile for Children. Parents completed child outcome measures and a questionnaire about their own coping strategies and their distress (using the Coping Health Inventory for Parents and the General Health Questionnaire. ). Measures of illness severity included a composite measure regarding the child's treatment, illness and hospital attendance, and a self-report health and social functioning measure. Children's coping with their illness was evaluated using the Kidcope Questionnaire and 4 coping styles were identified using factor analysis. Findings from previous research suggest that factors affecting adjustment to illness are interactive and have resulted in models of adjustment that need to be applied to field research. Therefore, coping was examined both as a moderator and a mediator of the effect of severity of illness on psychological outcome. Descriptive findings indicated significantly higher levels of psychological difficulties in these children compared to normative values, supporting previous findings of other children with chronic disease, but no differences in mean levels of self-esteem. An effect of illness severity on outcome was seen for the self report measures of illness severity only. Maternal variables did not have an effect on child's coping, although there were some effects of gender on coping strategies endorsed. Coping acted as a mediator in one circumstance, where a maladaptive coping style mediated the relationship between social functioning and psychological adjustment. Coping acted more consistently as a moderator when higher levels of maladaptive coping style moderated the relationship between self reported illness severity and psychological outcome. The findings, though tentative, have implications for further research and clinical practice.