To investigate associations between risky and pathologic internet use with depression, deliberate self-harm and suicidal behaviour among a representative sample of German adolescents. A total of 1,435 students (48% boys, 52% girls) from the area of Heidelberg/Germany were recruited during the SEYLE study, a European school-based intervention study and completed an assessment of different questionnaires, including the Young Diagnostic Questionnaire for the assessment of risky and pathological internet use, the Beck Depression Inventory, the Deliberate Self Harm Inventory, and the Paykel Suicide Scale. 80.7% of the students reported regular, 14.5% risky, and 4.8% pathological internet use. The risky and the pathological internet users showed significant higher rates of depression, deliberate self-harm and suicidal behaviour compared to students with regular internet use. Remarkably, there were no significant differences of levels of depression and suicidal behaviour between risky and pathological users. These results suggest that not only pathologic internet use but also risky internet use is associated with symptoms of depression, self-harm and suicidal behaviour. Therefore, more attention should be paid to adolescents with risky internet use for the early recognition of depression, self-harm and suicidality in adolescence.