The surgical managagement of two cases of lateral ventricular subependymal giant cell astrocytoma, arising in the head of the Caudate nucleus, and causing hydrocephalus due to obstruction of the foramen of Monro is described. One lesion, in a patient with tuberous sclerosis, was resected using a transcallosal approach and the other, in a patient with no stigmata of tuberous sclerosis, using a frontal, trans-cortical transcystoventricular approach. The microsurgical aspects of excision and pathological anatomy of both tumours were very similar. Following tumour excision and pellucidotomy both patients had partial resolution of their hydrocephalus with complete resolution of their preoperative symptoms. The merits of transcallosal and transcortical approaches to these lesions are discussed.