Objective: To present the case of a boy with a late diagnosis of precocious puberty and its consequences. Case Report: A boy of 7 years and 11 months enters the paediatric emergency room with vomiting, diarrhoea and signs of dehydration. His mother referred appearance of secondary sexual characters since he was 5 years old. A prepubertal testicular size (2,5 mL) was observed, with high values of 17-hydroxiprogesterone and testosterone, a prepubertal response in the stimulation test of GnRH, a very advanced bone age (14 years) and a predicted adult height of 147 cm with a target height of 168 cm. The diagnosis of congenital suprarenal hyperplasia was done and the treatment with hydrocortisone was initiated. Subsequently, the patient showed an increase of the testicle volume (8 mL) and a pubertal response in the test of GnRH. In this moment, the treatment with GnRH analogue was associated. This is a peripheral precocious puberty that secondarily triggered a central precocious puberty. Conclusions: The sex steroids peripherally produced may accelerate the maturation of the hypothalamus- hypophysogonadal axis getting to a mixed aetiology of the precocious puberty (peripheral and central). The early diagnosis and treatment could reduce the impact on the height and sexual development.