Duchenne muscular dystrophy (DMD) is a progressive, impairing, life-limiting disorder of childhood. Little is known about how siblings adapt to this. The aim of this study is to document psychosocial adjustment in siblings of patients with DMD. Healthy siblings (11–18years old) of young people with DMD attending a specialist paediatric centre and their parent/main carer took part. Parents, siblings and teachers completed a battery of questionnaires: (i) to assess psychiatric risk the Strengths and Difficulties Questionnaire (SDQ), General Health Questionnaire (GHQ), Hospital Anxiety and Depression Scale (HADS); (ii) to measure general wellbeing: SF-36; (iii) to document DMD illness disability: Functional Disability Inventory (FDI); (iv) to assess family function and life stresses for the unaffected sibling: Family Assessment Device (FAD), Family Burden Interview Schedule and Life Events Checklist. Forty six/77 eligible siblings (24 females/22 males); (mean age 14years (SD 2.3)) took part. Although their mean psychological functioning and wellbeing questionnaire scores were comparable to normative data, there was a trend for more siblings scoring at high-risk for psychological (mainly emotional) problems. Weak/moderate associations with psychological symptoms in siblings varied according to informant and included the following factors: closeness in age to the affected sibling; older sibling age; extent of wheelchair use, burden of illness on family interactions, and siblings reporting high impact of illness on their lives. Psychological symptoms were also associated with less sibling involvement in patient care, with broader psychosocial and family disadvantage and with life stresses. Siblings have an increased risk for emotional problems, which appears influenced by specific illness factors.