On neuropathological investigation, primary elevated MIB-1 labeling indices ≥ 9% were analyzed regarding the correlation with strong CD68+ macrophage infiltrates; 40% of primary meningiomas demonstrating an MIB-1 labeling index ≥ 9% were found to have diffuse CD68-positive macrophage infiltrates, whereas in the group of patients with primary MIB-1 labeling indices < 9%, increased CD68+ macrophage staining was found in only 16.7% of primary cranial meningiomas. This evidence concerns the gene MIB1 and meningioma.