We assessed a 6-year-old girl who developed status epilepticus and exhibited transient aphasia during the course of acute encephalopathy with late reduced diffusion, and who had a residual reading disorder in the recovery period. The aphasia appeared to be fluent aphasia and anomia, suggesting that the reading disorder during the recovery process was due to impairment of the phonological process. There were no biphasic seizures during the course of the patient's illness, but this case was acute encephalopathy with febrile convulsive status epilepticus (AEFCSE) from the standpoint of the characteristic imaging findings. Lesions in the left parietal and temporal lobes were detected on MRI diffusion-weighted images and by SPECT and MRS, and they appeared to be the lesions responsible for the aphasia and residual reading disorder. This case appears to be important from the standpoint of assessing the pathophysiology and the treatment of coexisting illness observed in acute encephalopathy.