Objective: To investigate the relationship between the apparent diffusion coefficients (ADC) value obtained from magnetic resonance imaging (MRI) and histopathologic grade of meningiomas. Study Design: Observational study. Place and Duration of Study: Department of Radiology, Istanbul Medeniyet University, School of Medicine, Istanbul, Turkey between January 2015 and June 2019. Methodology: Data of 45 patients with meningiomas, who underwent surgery at the University Hospital, were retrospectively reviewed; 28 patients were enrolled in the study. The pathology preparations of the patients were re-evaluated according to the World Health Organisation (WHO) 2016 classification updated by a neuropathologist. ADC values were measured in a standard region of interest range from the three consecutive sections where the mass had the largest width and from the opposite white matter. Results: Fourteen patients (50%) were diagnosed with WHO grade I tumor, 11 with grade II (39.3%), and three with grade III (10.7%). The ADCmin value was found statistically significant for the differentiation of tumor grades (p = 0.018). The cut-off point of the ADCmin value was 0.634x10-3mm2 s for the differential diagnosis of grade I and grade II/III meningiomas. The sensitivity of the cut-off value was found as 86% and its specificity as 57%. The patients with increased cellularity and Ki67 proliferation index had statistically significantly lower ADCmin values (p = 0.025). Conclusion: The data of this study show a significant difference in the ADCmin values on MRI between low- and high-grade meningiomas. A negative correlation was found between histopathologic grade and ADCmin