PURPOSE: Atypical meningioma is an intermediate type, between benign and malignant meningiomas, and has ahigher recurrence rate and poorer prognosis than the benign type. The purpose of this study was to evaluate thedifferential imaging findings between atypical and benign meningiomas. MATERIALS AND METHODS: Over a five-yearperiod, 11 acses of atypical meningioma (in ten patients) were pathologically proven, and 30 benign meningiomaswere collected consecutively over 6 months. In retrospective analysis, the MR findings of atypical and benignmeningiomas were compared with respect to tumor respect to tumor margin, lobulation, intra-/peritumoralhemorrhage, cystic change, heterogeneity peritumoral edema, enhacement of adjacent meninges, invasion of adjacentvenous sinus and adjacent bony change. RESULTS: Significant differential MR findings between the two groups wereill-defined tumor margin(atypical-27%;benign-0%), lobulation(82%;43%), heterogeneity(73%;30%), and peritumoraledema(100%;47%). With regard to moderate edema, there was no significant difference between the twogroups(36%;23%), and with regard to intra-/peritumoral hemorrhage, cystic change, enhancement of adjacentmeninges, invasion of adjacent venous sinus, and adjacent bony change, MR findings between the two groups were notsignificantly different. CONCLUSION: The MR findings of atypical meningioma are significantly different inseveral ways from those of benign meningioma, and these differences may help differentiate the two types.