True precocious puberty occurs as a result of the premature release of luteinizing hormone-releasing hormone from the hypothalamus, which stimulates the secretion of the pituitary gonadotropins, which in turn stimulate the gonadal sex steroids. The differential diagnosis of true precocious puberty includes cerebral and idiopathic categories. This differentiation, which cannot be made endocrinologically due to similarities in pituitary gonadotropin and sex steroid levels, may be facilitated by high-resolution CT. A CT study of 90 children (73 girls and 17 boys) with true precocious puberty was performed at the NIH to detect cerebral causes of their precocious puberty. Thirty-four cerebral abnormalities were demonstrated in 32 children, 16 boys and 16 girls. These included hypothalamic hamartomas (17), hypothalamic astrocytoma (one), optic chiasm lesions (six), ventricular abnormalities (eight), arachnoid cyst (one), and teratoma (one). The CT appearance of these cerebral abnormalities is discussed and related to the endocrinologic findings and natural history of true precocious puberty. A practical neuroradiologic approach to the evaluation of children with precocious puberty is presented.