In this paper, data derived from the national database of the Italian surveillance system for bovine spongiform encephalopathy (bse) are used to describe the Italian epidemic of bse. Two data flows were established to collect the results of active and passive surveillance, and 25 regional laboratories were involved. The National Reference Centre (cea) was in charge of the data analysis. Crude and age-standardised estimates of the prevalence and incidence of bse were obtained to describe the distribution of the disease in terms of the main risk factors (age, breed and herd size), year of birth, time of diagnosis and geographical location. The increased risk was calculated in terms of the incidence rate ratio. During the five years since January 2001, 128 cases of bse were identified in domestic cows and four were identified in imported cattle. All but one of the cases were detected through active surveillance. The risk of the disease was highest in dairy stock and in large herds. The northern regions of Italy had an incidence of bse 2·6 times higher than the southern regions. There was a clear decline in the age-standardised prevalence, from one positive case per 10,000 tests in 2001 to one per 100,000 tests in 2005.