Intracranial germ cell tumours (IGCT) are a rare, heterogenous group of lesions, which most frequently arise in the pineal and suprasellar regions.IGCT can be classified as germinomas, non-germinomatous germ cell tumours (NGGCTs) and teratomas.The term growing teratoma syndrome (GTS) was first described by Logothetis for extracranial germ cell tumours that demonstrated paradoxical growth of solely mature teratomatous elements despite normalisation of tumour markers We describe a case of intracranial growing teratoma syndrome (iGTS), notable for its occurrence in an adult, the long interval following the completion of treatment (consisting of radiation therapy alone) to development, and the purely monodermal character of the mature teratomatous mass..To our knowledge, this is the first report of such nature in the literature.