In rare cases precocious puberty is induced by paraneoplastic production of sex steroids. Therefore, a careful inspection of the genital organs should routinely be included in a pediatric clinical examination. Differential diagnosis of precocious puberty includes adrenocortical tumors and adrenal enzyme deficiencies as well as primary hepatic tumors with endocrine activity in addition to central causes. In the case described here the cause was a hepatoblastoma with paraneoplastic production of testosterone.