Cognitive impairment is frequent in temporal lobe epilepsy (TLE). In particular, specific deficits in temporal lobe related functions occur, but deficits in extratemporal lobe functions and global intelligence are also found. The degree and type of the impairment are first determined by structural damage and functionally dynamic factors. Most cognitive problems in TLE are already detectable at, or even before, the onset of the epilepsy. Accumulation of damage during the course of chronic epilepsy may add to this. This additional damage may be caused directly by severe seizures, head trauma, intoxication etc., or indirectly by interference of the epilepsy with mental development. Surgical treatment of TLE may also affect the cognitive outcome of patients with chronic TLE, with a risk of additional impairments on the one hand and functional recovery due to seizure control on the other hand. With regard to patient-associated factors, better baseline performance, younger age, cerebral plasticity, and good mental reserve capacities are associated with a better outcome. With regard to treatment-associated factors, prevention of additional brain dysfunction/damage and successful seizure control are important.