The main goal of this study was to investigate the precise hormone dysfunction that leads to dysfunctional uterine bleeding (DUB) in adolescent girls so that, with the appropriate therapy, the occurrence of organic dysfunctions of their reproductive function can be prevented. This study included 70 adolescents with DUB aged 14.70 +/- 1.70 and 30 healthy adolescents aged 13.7 +/- 1.83. Hormone examinations indicated the presence of three typical endocrinological findings of the adolescents with DUB: the first group with FSH values within the normal range, but low LH values, the lower value of estradiol and absence of hyperandrogenism; the second group with higher LH values and normal FSH values but one third with hyperandrogenism; and the third group with normal FSH and LH values, but with hyperinsulinemia and hyperandrogenism. Comparing the hormone values obtained in the control group and the group with DUB, we have concluded that hyperandrogenism, hyperinsulinemia, lower values of progesterone, and dysfunctions in secretion of gonadotropin are statistically important factors for the origin of juvenile bleeding.