Ependymomas account for 2% of all intracranial tumours in adults. Considerable controversy continues to exist with regard to their prognostic factors and therapeutic management due to the rarity and the heterogeneity of series reported so far. The authors report a retrospective study of a homogenous population of 152 adult patients harbouring intracranial ependymomas from 24 French Neurosurgical Centres between 1990 and 2004. All clinico-radiological and follow-up data were analysed and a central pathologic review was performed by two confirmed neuropathologists. The 5- and 10-year overall survival rates were 84.8 and 76.5%, respectively; the 5- and 10-year progression-free survival rates were 63.5 and 52.8%, respectively. On multivariate analysis, overall survival rates were associated with histological grade (P < 0.001), extent of surgery (P = 0.006), patient age (P = 0.004) and patient Karnofski performance status (P = 0.03). The multivariate analysis also revealed that the risk of recurrence was associated with high histological grade (P < 0.001), incomplete resection (P < 0.001) and Karnofski performance status < or = 80 (P = 0.04). The impact of radiotherapy was found to be beneficial for incompletely resected low-grade ependymomas and to a lesser extent for completely removed high-grade tumours. In association with Karnofski performance status and extent of surgery, histological grade is a major prognostic factor in adult intracranial ependymomas. The application of a simple and reproducible grading scheme using objective anaplastic criteria seems useful practically and clinically applicable. The role of adjuvant radiotherapy for patients with incompletely resected low-grade ependymomas seems to be beneficial but remains to be addressed for high-grade tumours.