Aim. The aim of the article is to partially verify the theoretical concept of depressive symptoms in adolescents, based on KID IO B1, as well as to check the accuracy of the questionnaire. Method. The KID results from an untreated sample population of 15-year-olds were statistically analysed. Of the 1118 KID IO B1 questionnaires submitted, 594 (246 boys and 348 girls) underwent factor analysis, of which 297, i.e. half, gained a result higher than the diagnostic threshold for depression. In search of the presence of general factors, as well as to verify the principles used to categorise depressive symptoms according to clinical criteria, analysis of the factors using methods consisting of oblimin, quatrimax and varimax rotations was carried out separately and combined for both genders. Results. The following new factors were distinguished for boys: I - lowered mood, and anxiety, II - self-destruction, III - apathy, cognitive disturbances, IV - somatic symptoms, V - somatisation, apathy, self-destruction, VI - boredom and avoidance of social contact, and for girls: I - lowered mood, lack of consideration for future repercussions, II - lowered drive, learning difficulties, cognitive and motivational disturbances, III - anxiety, IV - dysphoria with self-destruction, V - self-destruction, VI - eating pattern disturbances. Conclusions. Depression, as derived from factor analysis of the KID IO B1 questionnaire positions, is heterogeneous. Theoretical division of symptom groups, relating to the specific scale in the questionnaire, was confirmed to a very small degree through the analysis of the factors. The list of factors in genders differs. The groups of symptoms appearing in both genders gained from analysis are different in boys and girls with one exception, which may partially result from the different factor overviews of depressive symptoms in both genders.