OBJECTIVE: To determine the incidence of epilepsy in a general practice population and its variation with socioeconomic deprivation. DESIGN: Prospective surveillance for new cases over an 18 or 24 month period. PARTICIPANTS: All patients on practice registers categorised for deprivation with the Carstairs score of their postcode. SETTING: 20 general practices in London and south east England. MAIN OUTCOME MEASURE: Confirmed diagnosis of epilepsy. RESULTS: 190 new cases of epilepsy were identified during 369 283 person years of observation (crude incidence 51.5 (95% confidence interval 44.4 to 59.3) per 100 000 per year). The incidence was 190 (138 to 262) per 100 000 in children aged 0-4 years, 30.8 (21.3 to 44.6) in those aged 45-64 years, and 58.7 (42.5 to 81.0) in those aged > or =65 years. There was no apparent difference in incidence between males and females. The incidence showed a strong association with socioeconomic deprivation, the age and sex adjusted incidence in the most deprived fifth of the study population being 2.33 (1.46 to 3.72) times that in the least deprived fifth (P=0.001 for trend across fifths). Adjustment for area (London v outside London) weakened the association with deprivation (rate ratio 1.62 (0.91 to 2.88), P=0.12 for trend). CONCLUSIONS: The incidence of epilepsy seems to increase with socioeconomic deprivation, though the association may be confounded by other factors.