The present study examines the 10-year time-trend changes of adolescent psychiatric symptoms, smoking and alcohol use. Representative population-based samples with same methods at two time-points, same age range and with 10-year period between the time points were gathered in Finland to investigate secular changes in adolescents' emotional and behavioral problems. Seventh and ninth grade students filled in the Strengths and Difficulties Questionnaire (SDQ) and questions regarding alcohol use and smoking anonymously during a school lesson in 1998 (n = 1458) and 2008 (n = 1569). The self-reports of SDQ showed substantial stability in emotional and behavioral problems from 1998 to 2008. There was no increase between the two timepoints in self-reports of SDQ total, conduct, hyperactivity, emotional or peer problems when using the 90th percentile clinical cut-off points. However, there was a trend showing decreasing prosocial behavior among girls indicating that proportions of adolescent boys and girls having problems in prosocial behavior have converged, The self-reported alcohol use, drunkenness and cigarette smoking decreased within the 10-year time period. Of alcohol use, the number of non-users increased from 44 to 63 % between the years 1998 and 2008. Similarly, the proportion of non-smokers increased from 56 to 68 %. Although rates of substance use declined within the 10-year study period, drunkenness-oriented alcohol use and regular smoking are still prevalent among Finnish adolescents.