People with epilepsy are at increased risk of cognitive deficits as a result of various factors: structural brain lesions, genetic background, the effect of seizures themselves, psychosocial factors and adverse effects of antiepileptic drugs. The major cognitive effects of antiepileptic drugs are impaired attention, memory, vigilance, and psychomotor speed, but secondary effects on other cognitive functions can be seen. The adverse cognitive effects of antiepileptic drugs are offset in part by reduced seizures. Antiepileptic drugs-induced cognitive side effects are increased with rapid initiation, higher dosages, and polytherapy. Some patient groups may be at particular risk of adverse cognitive effects of antiepileptic drugs (e.g. elderly, children, fetus). The ultimate therapeutic goal is to control seizures with no or minimal side effects. Multiple studies have demonstrated that antiepileptic drug therapy may have consequences on cognitive function. Most of new antiepileptic drugs are at least as effective as the “old” antiepileptic drugs and, in general, they seem to be better tolerated than the old drugs. The new antiepileptic drugs might have less influence on cognitive functions but the aspect has not been systematically studied.