Abstract
A unique set of identical twin boys with spinal and intracranial meningiomas is described. Three distinct spinal tumours and one intracranial one were removed surgically. One intracranial meningioma has been symptomless, so far. The red cell and leucocyte groups of the two patients were found to be identical, and the probability of their being monozygous was estimated from these data as being 0·932 (Appendix).