The management of pineal tumours remains controversial. During 1994 we treated four consecutive adults (16-44 yrs) harbouring a pineal tumour with a neuroendoscopic procedure. All of them presented with hydrocephalus. Pre-operative workup included cranial computerized tomography (CT), craniospinal magnetic resonance imaging (MRI) and serum levels of biological tumour markers. The endoscopic procedure consisted of a third ventriculostomy followed by biopsy with a flexible, steerable neuroendoscope. Histological diagnosis was achieved in three patients who no longer required a shunt device. Recorded complications were: bleeding during ventriculostomy that prevented us from obtaining a good sample for biopsy, short-term memory loss that cleared over a two-week period, and transient increase of pre-operative hemiparesis. Complications and morbidity are emphasized so as to be avoided with further technical experience. Neuroendoscopy affords a minimally invasive way of reaching three objectives by one-step surgery in the management of pineal region lesions: 1) CSF sample for analysis of tumour markers. 2) Treatment of hydrocephalus by third ventriculostomy. 3) Several biopsy specimens can be obtained identifying tumours which will require further open surgery or adjuvant radiation and/or chemotherapy.