Among 716 patients with intracranial blastomatous changes 74 showed diplopia as a consequence of involvement of the oculomotorius, trochlearis or (and) the abducens nerve. Diplopia as primary symptom of disease was observed in 20 cases. Patients with isolated initial diplopia were on average 10 years younger than patients where diplopia occurred only in the further course of the tumour. There were no preceding other diseases demonstrable in patients with initial diplopia. Papilloedema did not occur significantly more frequently in them than in patients with diplopia as secondary symptom. In rare cases latency between occurrence of diplopia and further symptoms may be months to two years. For this reason exact neurologic and ophthalmologic follow-up controls, particularly in young patients with isolated persistent diplopia, are required.