“…This mechanism has been used to explain preco cious puberty in patients with germ cell tu mours of the testis, liver and other sites [7,8]. Surprisingly, there are few cases documented by immunoassay of intracranial tumours se creting either BhCG, with [10][11][12][13][14] or without [2,5,7,9,15,16] precocity, or aFP alone [17] or in combination [5,6], Below the age of 18 years approximately half the tumours in the pineal region are germ cell in origin [18] . Based on a review of the histological findings in 35 cases [2] we estimate that more than half of these would have either tropho blastic elements and secrete BhCG or endodermal sinus tumours and secrete aFP.…”