The onset of bipolar disorders before the age of 10 is rare. First manifestation occurs most frequently between the age of 15 to 30. Children of a parent with bipolar disorder are at a fivefold risk for developing a bipolar disorder. Therefore, an elaborate family-history is essential for the assessment of potentially manic or depressive symptoms in children and adolescents. Basically, for all age groups the same diagnostic criteria according to ICD 10 are applied. Due to the differing symptoms for children and adolescents the finding of a diagnosis is considerably harder than for adults. Manic episodes before the age of 10 are characterized by increased activity, more risk taking behaviour and elevated emotional instability. In adolescents, however, behavioural disturbance with antisocial behaviour and drug-abuse are more common. Thus, typical misdiagnosis as ADHD or conduct disorders for children and adolescents are frequent. Aggravating the complexity, in up to 90 % both differential-diagnosis may occur as comorbid disorders. Furthermore, psychotic symptoms are more common than in adults and dysphoria is more likely than euphoric or depressive mood. Asymptomatic intervals rarely exist, whereas "ups" and "downs" in rapid succession are prevailing (rapid cycling). An early diagnosis, leading specific treatment, is essential for the prognosis of bipolar disorders. Additionally, structural (CCT or MRI) and laboratory examination are essential to expel endocrine or brain-organic diseases. Besides psychotherapeutic and psychoeducative methods, always including parents and attached persons, the psychopharmacological treatment is a major part of a multimodal treatment. The available substances partly have been in use for years and are appropriate for youngsters. These include mood stabilizers like lithium, divalproex and carbamazepine, which provide besides their acute antimanic effects also relapse-prophylactic properties. In addition atypical antipsychotics like risperidone, olanzapine and quetiapine have gained more and more importance in the treatment of manic states in children and adolescents during the last years. However the use of antidepressants in children and adolescents should be considered with great caution due to arguable efficacy and potentially severe adverse effects, i.e. amplification of suicidal ideation.