Ten survivors of medulloblastoma were examined for residual opthalmological signs. Gaze-evoked nystagmus occurred in six children, four of whom also had pronounced upbeat nystagmus. This is a rare and specific type of nystagmus associated with lesions of the cerebellar vermis and medulla, and has not been described previously as a long-term sequel of medulloblastoma. The recognition of upbeat nystagmus is important because visual acuity may be reduced in upward gaze and difficulties at school may ensue for these children, who may be already intellectually and behaviourally compromised.