Although multicentric glioblastomas are relatively rare, their occurrence is not an extreme rarity. A multicentric lesion should always be thought of when the symptoms cannot be related to a single focus and when the special investigations do not confirm a single lesion. In our opinion the brain scintigram and the computer tomogram offer the best diagnostic possibilities at present. If the preoperative diagnosis has been made, then an indication for operation can be justified only if multiple tumours can be removed through one approach and, what is even more important, at one sitting. The cases demonstrated prove that this procedure can be successful. If, on the other hand, only one of several tumours is excised, then a fatal outcome is almost certain.