Cognitive dysfunction in people with epilepsy is a frequently encountered but also easily overlooked problem. In this article three patients with epilepsy are presented with cognitive problems due to a relapse of seizures, due to continuing absence seizures or as a consequence of deteriorating mental functions resulting from frequent complex partial seizures. In the last patient the decline in mental functioning was also demonstrated in a disseminated activation pattern on her fMRI, which contrasts with the localised activity as seen in controls on fMRI. Suggestions how to handle these problems in daily practice are given.