The case of a male child with Russel's syndrome due to a pilocytic astrocytoma located in the diencephalic region is presented. The diagnosis was made in the 16th month of age, but symptoms began in the 4th month of life, when he started losing weight By the time he was admitted weight was 6150g and he was 74cm tall, with an emaciated aspect, no panniculus adiposus, irritated, and with symptoms of intracranial hypertension. There was convergent strabismus, vertical nistagmus of the left eye and bilateral papilledema. Tendinous reflexes were exacerbated and he had spastic tetraparesis. The endocrine evaluation showed a basal raise of GH (23ng/ml), TSH (6.2mUI/l) and prolactin (26ng/ml). The first two hormones did not respond to the acute test with TRH, while prolactin had a poor response. He was submitted to radiotherapy with linear acceleration (total dose of 4000 rads) and surgery, during which the tumor could not be completely removed due to its large size. After 9 months, the child is doing well, with a considerable weight gain (2500g).