Objective. To study clinical features of depressive episode with the onset in late adolescence associated with the risk of bipolar affective disorder (BAD). Material and methods. Forty patients with BAD (ICD-10 F31), who experienced depressive state at the age of 15—18 years corresponding to the diagnostic criteria of «Depressive episode» (F32), were examined. The duration of follow-up was from 3 to 5 years. Clinical-psychopathologic, follow-up, statistical methods were applied. Results. Duration of depressive episodes did not exceed 6 months in 70% of patients with BAD. Characteristic clinical features included the frequent presence of psychomotor retardation, anergia, anhedonia, melancholy, irritability, affective instability with increased emotional reactivity, hypersomnia. Other «atypical» depressive symptoms were less characteristic. There was a significant incidence of suicidal tendencies, comorbid psychopathic-like behavioral disorders and substance abuse. In most cases, the depressive state was accompanied by a deterioration in social functioning and led to educational maladaptation. Conclusion. Characteristic clinical features of bipolar depression manifested in late adolescence were a relatively short duration, the prevalence of typical depressive symptoms (melancholy, psychomotor retardation), irritability, increased emotional reactivity, hypersomnia, a significant incidence of suicidal tendencies.