Diagnosis of the central origin of precocious puberty is easy in boys on the enlargement of the testes. In girls, conversely, diagnosis of central precocious puberty (CPP) may be difficult, as isolated development of the breast may initially be the only feature. Differentiation of CPP and premature thelarche is nevertheless essential, as CPP always requires neuroradiologic investigations to look for an intracranial space-occupying lesion and may indicate inhibitory treatment. CPP is usually idiopathic in girls and tumor-related in boys. Early secretion of sex steroids increases the rate of growth and bone maturation and may lead to final short stature. LHRH analogues represent a breakthrough in the treatment of CPP.