A unilateral cortical oedema in association with coxsackievirus B infection is reported. A 10-year-old girl presented with right hemiparesis and complex partial seizures. The cerebral MRI showed a unique pattern of isolated unilateral cortical oedema sparing the white matter with intravascular gadolinium enhancement of the left hemispheric sulcal veins. With anticonvulsant medication, the patient recovered within two weeks and MRI abnormalities were completely resolved after four weeks, whereas the EEG left hemispheric slowing showed delayed normalisation over the following five months.