To identify factors linked with emotional and behavioural problems in school age (6-to 17-year-old) children of women with breast cancer. Reports of children's emotional and behavioural problems were obtained from patient mothers, their healthy partners, the children's teacher and adolescents using the Child Behaviour Checklist and Mental Health subscale of the Child Health Questionnaire. Parents reported on their own level of depression and, for patients only, their quality of life. Family functioning was assessed using the Family Assessment Device and Cohesion subscale of the Family Environment Scale. Using a cross-sectional within groups design, assessments were obtained (N ¼ 107 families) where the patients were 3 -36 months postdiagnosis. Risk of problems in children were linked with low levels of family cohesion, low affective responsiveness and parental over-involvement as reported by both child and mother. Adolescents reported family communication issues, which were associated with externalising behaviour problems. Maternal depression was related to child internalising problems, particularly in girls. Whether the mother was currently on or off chemotherapy was not associated with child problems nor was time since cancer diagnosis. These findings held across child age. Where mothers have early stage breast cancer, a substantial minority of their school-aged children have emotional and behavioural problems. Such cases are characterised by the existence of maternal depression and poor family communication, rather than by the mother's treatment status or time since diagnosis. Targeted treatments, which focus on maternal depression and family communication may benefit the children and, through improved relationships, enhance the patients' quality of life.