Background: Precocious puberty (PP) is defined as the appearance of symptoms of puberty in girls before 8 years of age and in boys under 9. Statistically, it occurs much more frequently in girls, while it is a rare pathology in boys. Material/Methods: Over the period of 10 years, between 1999 and 2009, 39 girls and 17 boys aged 18 months - 9 years were diagnosed with precocious puberty, and treated at the Endocrinology Clinic. The following tests were performed in all children: physical and anthropometric examinations, abdominal ultrasound scan (US) with evaluation of adrenal glands, examination of testes in boys or breasts and pelvic organs in girls, evaluation of skeletal age and, in selected cases, CT scans of the abdomen, MRI of the CNS, and hormonal laboratory tests. Results: In the group of 17 boys the findings included: gonadotropin-dependent central puberty in 6 boys: idiopathic in 5 cases, and 1 case of a brain tumor - astrocytoma. Gonadotropin-independent precocious pseudopuberty was diagnosed in 11 boys: congenital adrenal hyperplasia in 5; in 1case - hyperandrogenism caused by overactivity of 5-a reductase; in 2 subjects - adrenal adenoma; in 2 boys adrenocortical carcinoma was diagnosed and Leydig cell tumor of testis in 1. Conclusions: 1. Precocious puberty occurs less often in boys, but in our population it was found in 17 boys of 56 treated children, which constituted as much as 30%. 2. Precocious pseudopuberty was found in 64% of the boys with PP. 3. Adrenal and testicular tumors were the causes of precocious puberty in the youngest group of boys aged 18 months - 6 years.