The proliferation indices (PIs) were determined in 33 meningiomas using two monoclonal antibodies to the Ki-67 antigen (Ki-67 and MIB1). PIs obtained using Ki-67 on frozen material were intermediate between the lowest and highest MIB1 PIs determined in paraffin wax sections. Preoperative embolisation did not influence Ki67 PI, but four of the 15 embolised tumours showed substantially increased MIB1 PIs around embolisation necroses. Proliferation can be reliably assessed in routinely processed meningioma tissues using MIB1; and increased perinecrotic PIs may occur in embolised meningiomas without being an indication of malignancy.