(1) Meningiomas are perhaps the most interesting and versatile of all brain tumours. They may form calcium, cartilage or bone, and may cause secondary bone production and/or bone destruction.(2) Meningiomas may be occasionally mistaken for sellar or extrasellar lesions of other origin.(3) Although usually found in older individuals, meningiomas may occur in children.(4) Not infrequently the only röntgen manifestation of a meningioma may be increased vascularity of the skull, slight thinning of the calvarium, slight irregularity of the inner table, or a very small hyperostosis.(5) The hyperostoses produced by meningiomas have been classified and may be diffuse or nodal and predominantly osteoblastic or osteolytic.(6) The diffuse tumerous hyperostoses must be differentiated from the spongy type of osteoma.(7) Osteoclastic hyperostoses occur more frequently than commonly believed and may appear similar to metastatic carcinoma, oesinophilic granuloma, monophasic Paget's disease and leukemic lesions of the calvarium.(8) An unusual diffuse osteolytic change occurring in the floor of the middle fossa and a cystic type of hyperostosis are described.(9) Röntgenographs of excellent technical quality and a high index of suspicion are required for demonstration and recognition of minimal röntgen changes not infrequently produced by meningiomas.(10) Demineralisation of the sphenoidal ridge may be the only röntgen manifestation of a sphenoidal ridge meningioma and must be differentiated from a normal variant of the ridge and demineralisation produced by aneurysm, metastatic carcinoma, or a glioma.(11) The hyperostosis produced by large outer sphenoidal ridge “en plaque” tumours is striking and pathognomonic.(12) Suprasellar meningiomas may produce a minimum of röntgen changes with little or no deformity of the pituitary fossa.(13) Basilar meningiomas are rare and may produce a demineralisation of the base of the skull which is demonstrable only in the röntgenographs of the base of the skull.(14) The röntgen changes produced by parasagittal meningiomas are variable in type and location.(15) Multiple meningiomas occur more frequently than generally believed.(16) The hyperostosis produced by meningiomas may be much larger or much smaller than the underlying tumour.