Cognitive impairment associated with antiepileptic drug (AED) therapy represents a particular problem, especially in the young and elderly. Lamotrigine (LTG) is a new-generation AED that is effective and well tolerated in both the elderly and children. Existing data suggest that the cognitive deficits commonly associated with AED therapy are not commonly observed in patients receiving LTG as monotherapy, and, when LTG is used as an add-on therapy, any existing cognitive problems are not exacerbated and in some cases are clearly improved. Here we have reviewed previous studies that have examined the impact of LTG therapy on cognitive functioning. We have considered data from monotherapy and add-on clinical studies and also more indirect evidence from volunteer studies and from neurophysiological evaluations in epilepsy patients. These data suggest that the impact of LTG on cognition is at least equivalent to that of existing standard AEDs and, in many cases, the use of LTG is associated with improved cognitive functioning, which is not seen with standard AEDs. We have also considered the wider implications of patient quality of life, accepting that cognitive function may form an integral part of the patient's perceived quality of life.