Résumé : We report a girl with refractory partial seizures since 7 years of age, secondary to right frontal cortical dysplasia, who developed MRI and SPECT abnormalities in the contralateral hemicerebellar cortex. These became more marked, leading to left hemicerebellar atrophy. Crossed cerebellar diaschisis has been described mostly in hemispheric stroke and supratentorial tumours, but less often in epilepsy. It is usually a transient phenomenon. This report shows that crossed cerebellar diaschisis can develop within two years of seizure onset and evolve over time.