Epidemiological incidence data are important to determine those who are at risk of epilepsy and to understand the aetiology of the condition. A number of studies have been reported recently, which allow comparisons across populations. There appears to be geographical variation in the incidence of epilepsy, with a higher incidence in rural South America than in developed countries: no large scale incidence studies have yet been carried out in Africa or Asia. A consistent pattern suggesting that the onset of epilepsy occurs at the extremes of life has also been shown. Although a number of factors are often identified as causes of epilepsy, studies have identified a definitive aetiology in only one-third of all newly diagnosed cases. Epidemiological studies have, however, confirmed the importance of postnatal insults and quantified the risk. Family history may also be considered a risk factor for epilepsy in epidemiological terms.