This study examines whether health risk behaviour in adolescence can be predicted by self- and by parental reports of psychopathology (externalizing and internalizing symptoms) assessed two and four years earlier. A total sample of 366 fourth graders participated in a longitudinal study with measurements taken in grades 4, 6, and 8. In grades 4 and 6 the children completed the Youth Self Report (YSR) while their parents completed the Child Behaviour Checklist (CBCL). In grade 8, the children reported their risk behaviour (smoking, sexual activity, dietary behaviour and suicidal tendencies). Results reveal that cross-informant correlations for both symptom-scales are low to medium and tend to increase slightly from grade 4 through 8. Children reported higher symptom-levels and changes over time than their parents. The predictability of risk behaviour in adolescence by reported psychopathology in grade 6 exceeds the predictability in grade 4. Results indicate that the predictability of risk behaviour by self-reports versus parental reports of psychopathology depends on the specific kind of health risk behaviour and the child's gender.