Olfactory neuroblastomas are rare malignant tumours of the nose arising from the olfactory epithelium. In a retrospective series of 18 cases and a review of the literature, the authors establish the main features of this tumour. They emphasise the difficulties of histological examination, often requiring immuno-cyt-chemistery and electron microscopy. They point out the value of a new classification, and confirm treatments being radio-surgical, with use of the combined rhino-neurosurgical approach when there is extension to the cribriform plate. They report a 5-year survival of 91.5%, with 87.5% at 10 years. The high incidence of lymph gland metastases (16.6%) is greater than that of local recurrence (11%) especially in the more advanced cases. The question of prophylactic treatment of the neck nodes is one to be considered.