Four cases of hypothalamic hamartoma leading to gelastic epilepsy, precocious puberty and behavioural disorders are reported. Cerebral neuroradiologic examinations revealed a tumor-like mass attached to the hypothalamus in the region of the mamillary bodies in all cases. Precocious puberty developed in the two girls at 4 and 13 months but in neither of the two boys, who both suffered behaviour disturbances in the form of aggressive outbursts. A total resection of the tumors of both boys led to histologic confirmation of hamartoma. One boy was free of seizures upon follow-up, whereas seizure frequency in the other boy was reduced, while his aggressivity increased. The cases are discussed in context of current therapeutic conceptions of gelastic epilepsy and central precocious puberty.
