PURPOSE: To describe the MR imaging findings of post-operative change and residual/recurrent tumor following resection of the glioma and to determine whether there are any specific MR imaging findings useful for differentiation of post-operative change from a residual/recurrent tumor. MATERIALS AND METHODS: We retrospectively analysed 71 post-operative follow-up brain MR images of 26 patients who had undergone surgical resection of intracranial glioma. They consisted of 49 MRI studies of 12 patients with post-operative change and22 MRI studies of 14 patients with residual/recurrent tumors. The follow-up MRI examinations were performed fromone to 75 months after tumor resection. The lesion was defined as post-operative change when any enhancing lesion disappeared or diminished during follow-up MRI studies of at least 20 months. The diagnosis of residual/recurrent tumor was established when on MR images, lesion size increased definitively during the follow up period of between four and 66 months ; residual/recurrent tumors were surgically proven in five patients. The shape, degree of contrast enhancement and time of appearance and disappearance of the lesions were analysed. RESULTS: Post-operative change consisted of hemorrhage(n=3), marginal(n=7) and nodular(n=1) enhancement of sugical bed, adjacent dural enhancement(n=9), extracerebral fluid collection(n=4) and only tissue defect(n=1). Hemorrhage was obseved at between two and eight months ; marginal and nodular enhancement of surgical bed were seen at between three and 30 months (usually less than one year) ; dural enhancement and fluid collection were seen at between three and 75 months. Residual/recurrent tumor appeared most frequently as enhancing solid nodules(n=7) or solidand cystic masses(n=2) followed by non-enhancing solid nodules(n=3). In five of seven cases, marginal enhancement of a residual/recurrent tumor appeared after more than one year. CONCLUSION: Marginal and dural enhancement around surgical tissue defects are the most common finding of post-operative change, whereas nodular enhancementis the most frequent finding of the residual/recurrent tumor. Marginal enhancement lasting longer than one year may, however, be an early finding of residual/recurrent tumor.