Objective: Worldwide there are frequent reports on increasing psychosomatic problems, anxiety, emotional distress, conduct problems, and depression among adolescents. Recently, it was contended that secular studies on such aspects of adolescent mental health can only be evaluated adequately when data on symptom prevalence are analyzed together with data on functional impairment Still, this has not yet been done in epidemiological time-trend studies on any aspect of adolescent mental health. Therefore, this study aims to investigate if, and to what extent, changes in adolescents' symptoms of psychosomatic problems are affected when data on functional impairment are taken into account simultaneously. Methods: A repeated cross-sectional population study relating self-reported symptoms of psychosomatic problems to functional impairment; covering the time-period 1988-2011 and including 19.823 adolescents 15-16 years old in eight cohorts in one geographically defined population (Varmland, Sweden). Results: The proportion of adolescents with psychosomatic problems had increased significantly from 1988 to 2005/2008. In all cohorts the proportion of girls with psychosomatic problems was significantly higher than the proportion of boys reporting symptoms. Over the same period, there was a corresponding significant increase of the proportion of participants with symptoms of psychosomatic problems in combination with functional impairment Adding functional impairment to the measure of psychosomatic problems decreased the prevalence rates, while the shapes of the trend-curves stayed congruent in form. Conclusion: The long-term pattern of increasing psychosomatic problems among adolescents remains evident, even when taking functional impairment data into account. Previously observed trends of a deteriorating adolescent mental health are thus consistent with this study.