Abstract AIMS It is well established that the surgical outcome is poorer in larger meningiomas. Vascular/ neural encasement and bone/dural/vascular invasion complicate surgical resection. Nevertheless, it is also likely that meningiomas will become biologically more aggressive with increasing size and tumor cell burden. To prove this hypothesis we studied radiological features of 316 meningiomas and correlated these features with tumor WHO-grade. METHOD 316 meningioma patients who were operated on and who received pathological diagnoses at one single institution were analyzed. Pathological grading was revised by one single neuropathologist according to WHO 2021 criteria. 123 high-grade (WHO grade 2 and 3) patients were initially selected and later substituted with a further 193 age and anatomical-location-matched individuals. Preoperative MRI studies were analyzed for size, hyperostosis, intratumoral calcification, mass effect, peritumoral edema, shape (globular/en-plaque), lobulation, cystic component, intratumoral heterogeneity, dural tail, and necrosis/hemorrhage. Univariate analysis as well as logistic regression were performed. RESULTS High-grade meningiomas were significantly more common to have lobulation (p: 7.111 x 10-8), necrosis/hemorrhage (p: 1.176 x 10-6), peritumoral edema (p: 3.421 x 10-6), intratumoral heterogeneity (p: 1.201 x 10-5), mass effect (p: 0.0002408), and cystic component (p: 0.003519) compared to WHO grade 1 meningiomas. Logistic regression indicated that tumor volume was an independent and significant parameter. High-grade tumors were significantly larger (40.83 cm3 vs 22.18 cm3, p: 3.518 x 10-6). Skull base meningiomas were of significantly lower grade (p: 0.001318). Mean volume was significantly higher in high-grade meningiomas. Mean tumor volume varied significantly among histopathological subtypes but was highest in anaplastic and atypical subtypes. Tumor volume was strongly correlated with mitosis (p: 2.353 x 10-6), hypercellularity (p: 1.22 x 10-4), spontaneous necrosis (p: 3.273 x 10-4), brain invasion (p: 0.02491), macronucleus (p: 0.05327), small cell (p: 0.09425), and ki-67 levels (p: 2x10-16). CONCLUSION Tumor size is strongly correlated with WHO grade in meningiomas.