A girl with congenital adrenal hyperplasia due to 21 hydroxylase (CYP 21, p450c21) deficiency is the reviewed case. The clinical features (virilisation, clitoromegaly, rapid somatic growth, accelerated skeletal maturation) and laboratory findings (high levels of plasma 17hydroxy-progesterone, corticotrophin--ACTH, testosterone and dehydroepiandrostenedione--DHEA, low level of plasma cortisol, high level of urine 17-ketosteroids, synacthen and luteinising hormone releasing hormone--LHRH test) and the response to hydrocortisone therapy pointed at heterosexual gonadotrophin independent puberty due to irregular production of cortisol caused by 21 hydroxylase deficiency that leads to elevated ACTH and 17-hydroxy progesterone secretion and makes congenital adrenal hyperplasia as entity. The six-month therapy resulted in the clinical and laboratory findings improvement, such as the decreased annual growth of body height and the stagnation in the development of the secondary sexual features.