Children with epilepsy are at increased risk for attention deficit/hyperactivity disorder (ADHD). It has been shown that the cerebellum plays a major role in the pathophysiology of ADHD. We aimed to clarify whether children with combined epilepsy/ADHD have the same neurocerebellar pathophysiology as children with developmental ADHD. Eight boys with combined epilepsy/ADHD, 14 boys with developmental ADHD, and 12 healthy boys were investigated using diffusion tensor imaging generating fractional anisotropy (FA) maps. Healthy controls exhibited more FA in the left and in the right middle cerebellar peduncle compared with children with combined epilepsy/ADHD, and more FA in the right middle cerebellar peduncle compared with children with developmental ADHD. Our data show deficient cerebellar connections in both patient groups and endorse the crucial role of the cerebellum in the pathophysiology of ADHD. Our results suggest that ADHD seen in epilepsy might have the same cerebellar pathology as in developmental ADHD.