AbstractBackgroundSchizophrenia (SZ) and bipolar disorder (BP) are causes of severe disability worldwide and parents’ severe mental illness (SMI) is associated with childhood adversity, and socio-emotional and cognitive problems in children. Yet, how parental BP and SZ affect educational attainment in offspring is still unclear.MethodWe included all children (N= 684.248) born and living in Denmark between 1986 and 1996 and their parents. Our follow-up lasted from 1986 until children's graduation in 2014. The main outcome variable was their school grades following their primary education. School outcomes were divided into four categories: not graduated, low-grade point average (GPA), medium GPA and high GPA. We then performed a multiple logistic regression with medium GPA as the reference category, with the children of parents without SZ or BP as the reference group.ResultsChildren of parents with SZ faced higher odds than their peers of not graduating primary education (OR 2.6), along with low GPA (odds ratios (OR) 1.6) and lower odds for a high GPA (OR 0.7). Moreover, it was the children of mothers rather than fathers with BP who had higher odds of not graduating primary education (OR 1.6). Lastly, child placement was associated with lower grades and lower graduation rates, and outcomes for children of parents with SMI were favorable compared with other children placed in care.ConclusionFor children, parental SZ is associated with lower grades and lower chances for graduating primary education. In contrast, the children of parents with BP were indistinguishable from the reference group regarding school grades. This signifies that specificity of parental severe mental illness is important in relation to educational achievement of children.