Purpose : The purpose of this study is to find helpful MR findings for predicting anaplasticoligodendrogliomas. Materials and Methods : Retrospective analysis of 46 MR images and 37 CT scans was performedfor 46 patients with pathologically-proven cerebral oligodendrogliomas. A neuropathologist graded the tumors asone of low-grade (n=16), intermediate-grade (n=12), or anaplastic oligodendroglioma (n=18). MR imaging featureswere retrospectively analysed with respect to histologic grading of the tumors. Results : Contrast enhancement wasobserved always in anaplastic group (17/17), in a portion of intermediate-grade group (4/10) but not in low-gradegroup (0/14). Peritumoral edema was observed infrequently in anaplastic group (4/18) or intermediate-grade group(1/12). Cystic changes (25/46) or calcifications on CT Scans (14/37) were not related with histologic grading.Grossly identifiable hemorrhage was rare in this series (2/46). Among the various imaging features, only tumorenhancement and peritumoral edema were statistically significant for trend test (p<0.05). Conclusion : Whenconsidering the diagnosis of oligodendrogliomas, the presence of contrast enhancement or peritumoral edema is ahelpful features suggesting anaplastic oligodendrogliomas.