Tumours involving the anterior skull base are a challenge in diagnosis and treatment. They may arise from the bony skull base itself, intracranially or from the sinonasal tract and orbit. It is often difficult to determine the site of origin of giant tumours as anatomical boundaries are frequently breached. Accurate imaging evaluation is useful in planning treatment and may help in the differential diagnosis. We review those CT and MRI features of giant anterior cranial fossa tumours which may be helpful in identifying a pre-operative diagnosis.