Backgrounds: Convulsive status epilepticus may cause reversible neuroimaging abnormalities. These cortical changes have been reported rarely in association with nonconvulsive status epilepticus. Objectives: To describe patients with cancer who had reversible magnetic resonance (MR) imaging abnormalities from nonconvulsive status epilepticus and whose altered mental status and MR imaging findings were initially considered to result from a structural lesion related to their underlying tumor. Design: Retrospective study. Settings: Department of Neurology at Memorial Sloan-Kettering Cancer Center, New York, NY. Patients: Eight patients with a diagnosis of nonconvulsive status epilepticus who underwent MR imaging. Results: Enhancing cortical abnormalities were observed on MR images in 4 (50%) of 8 patients with cancer who had impaired mental status and an electroencephalogram demonstrating seizure activity. Follow-up MR images showed neuroimaging improvement or resolution in all patients. Conclusions: Cortical enhancement on MR images in patients with cancer who have altered mental status may be due to nonconvulsive status epilepticus and not recurrent or metastatic tumor. If electroencephalography is not immediately available at initial evaluation, a trial of anticonvulsant therapy deserves consideration.