Background: This prospective study explores the ongoing impact of early and subsequent maternal depression on offspring behaviour in the early school years. Methods: Seventy five mothers recruited into a longitudinal study were assessed for symptoms of depression when their children were 4, 12 and 15 months, 4 years and later when the children were 6-8 years of age. Mothers, fathers, and school teachers were asked to report on children's internalising and externalising behaviour problems. Results: Exposure to maternal depression during the first postpartum year was related to mother reports of child internalising and externalising problems in the early school years. Although depression in the first year predicted later internalising problems, effects for externalising behaviour problems were mediated by concurrent depression. Relations between concurrent maternal depression and externalising problems were confirmed by teacher ratings. Interestingly, the severity of symptoms at four months was significantly correlated with behaviour problems seven years later. Limitations: Attrition over successive study contacts and therefore limited statistical power is acknowledged. Findings may be a conservative estimate of associations between maternal depression and later child behaviour problems. Also, the high prevalence of depressive symptomatology in the population from which the sample was drawn may limit the generalisability of results. Conclusions: Findings confirm the importance of early identification and treatment for mothers with postnatal depression, given the likelihood of ongoing depression and relations with later child behaviour problems. From a practical point, severity of early symptoms may be a reliable index of those mothers and children at greatest risk.