PURPOSE: This systematic review aimed to identify the role of Ki-67 as a prognostic factor in estimating tumor grade and the radiation response in meningiomas. METHODS: A systematic search of the literature on meningiomas was carried out through the PubMed, Scopus, and EBSCOhost databases according to the PRISMA guidelines. RESULTS: Our search resulted in 465 collected articles, 15 of which satisfied the eligibility criteria. Twelve studies reported the correlation between Ki-67 and meningioma grade. Two other investigations reported the relationship between Ki-67 and the radiation response in meningioma, and one failed to capture the association between Ki-67 and the radiation response in meningioma. CONCLUSION: The Ki-67 proliferation index has a uniform correlation with meningioma grade. Two of the 3 studies on the correlation of Ki-67 with the radiation response in meningioma patients reported that patients with a higher Ki-67 responded better to radiation therapy.