Background: This study investigated the relationship between parental personality patterns and internalising and externalising behaviour problems in a clinically referred sample of children (aged 4-8) and adolescents (aged 12-18). Methods: Data from families involved in two clinical trials in Victoria, Australia were analysed (n = 59). Families were administered the Millons Clinical Multiaxial Inventory-III (MCMI-III) which reports personality patterns consistent with Axis II disorder and an Achenbach measure of mental health as appropriate to child's age (Child Behavior Checklist (CBCL), Youth Self-Report (YSR), or Adult Self-Report (ASR)). Relationships between internalising and externalising behaviour problems, and parental personality patterns were examined via correlation and regression analyses. Results: The study found a positive correlation between parental borderline, paranoid, and avoidant personality patterns, and child and adolescent externalising behaviour problems. The relationships were generally stronger for adolescents than for children. However, no relationship was observed between parental personality patterns and internalising behaviour problems. Conclusions: These findings underline the importance of clinical assessment of the family ecology as a whole--including the interaction between parental personality patterns and child and adolescent behaviour and emotional problems. These findings contribute to the understanding of developmental risk factors for child and adolescent mental health and the transmission of psychopathology across generations. (Contains 4 tables.)