A retrospective study of 75 consecutive cases of spontaneous cerebellar haemorrhage was undertaken in order to evaluate the clinical features and natural history of this condition. A wide spectrum of clinical findings contributed to the poor clinical diagnostic accuracy of 23 per cent, with common misdiagnoses including brainstem stroke and vestibular or labyrinthine disturbance. Presentation with, or the later development of stupor or coma strongly correlated with poor outcome (severe disability or death; p = 0.002). The characteristics of conscious patients who remained stable were compared with those who subsequently deteriorated. The initial conscious state (alert, drowsy or confused), severity of symptoms and ataxia, and the size of haemorrhage on CT scan were not reliable prognostic indicators. However, the presence of bilateral gaze paresis, anarthria (present in eight cases), limb weakness, a systolic blood pressure above 200 mmHg and moderate hydrocephalus significantly correlated with a poor outcome. The presence of these signs warrants consideration of urgent surgical intervention at the time of diagnosis. Since no clinical or radiological findings excluded the possibility of further deterioration, careful monitoring in an intensive care unit is necessary within the first 48 h in those conscious patients who are likely to remain stable. Guidelines for making the clinical diagnosis and for selecting those patients who will require transfer to adequately equipped centres are suggested.