Background: Education profoundly affects adult socioeconomic status, so it is important to ensure that all children have the capability and opportunity to achieve educational goals.Aims: The study aimed to examine the relationship between mental-health during adolescence and upper secondary school completion and grades, which has received comparatively little research attention to date.Method: Longitudinal administrative and registered data were used to analyse the relationship between school achievement and prescriptions of psycholeptic and psycho-analeptic drugs. The sample consisted of all children born in Sweden in 1990 (n=109223), who were followed from birth to age 20. Logistic and OLS regressions were performed separately for boys and girls, controlling for birth health and family characteristics.Results: A negative relationship between mental-health problems and educational outcomes was found; this result was almost independent of the controls. Only minor differences between the sexes were detected.Conclusions: Poor mental-health during childhood correlated negatively with educational attainment. Given the strong link between educational success and adult life, more resources are needed to support children with mental-health problems.