The aim of this study was to identify risk factors associated with Neospora caninum seropositivity in sheep from the State of Alagoas, in the northeast region of Brazil. Twenty-six herds were selected, and blood samples were collected from 343 animals > 6-mo-old. The indirect fluorescent antibody test (IFAT) was used for serological diagnosis of N. caninum infection. Epidemiological questionnaires were applied for each herd to identify the risk factors associated with infection. Thirty-three (9.6%) animals tested positive for anti- N. caninum IgG antibodies, with titers ranging from 1 ratio 50 to 1 ratio 1,600. Fourteen herds (53.8%) presented at least 1 seropositive animal. Risk factors identified were property size <or= 30 ha (odds ratio = 7.23; 95% CI = 1.99-26.49) and source of water (wells + municipal + water courses) (odds ratio = 4.76; 95% CI = 1.23-18.47). This is the first ezootiological study of N. caninum infection in sheep to be carried out in the State of Alagoas. Preventive measures focusing primarily on water treatment should be taken to reduce the risk of infection by N. caninum .