Leptospirosis is a widespread zoonosis in tropical regions. The prevalence is unknown in the Colombian region of Uraba. A cross sectional study was conducted from March to October 2000 in order to determine the prevalence of Leptospira spp. antibodies and describe risk factors in nine counties in the region. The sample consisted of 582 individuals, who answered a questionnaire and had blood samples drawn to determine risk factors. Detection of Leptospira spp. antibodies was based on indirect inmunofluorescence and microagglutination. Seroprevalence was 12.5% (95%CI: 10.01-15.5). No differences were observed according to race, gender, occupation, age, living conditions, or time of residence in the area. L .interrogans serovar Grippotyphosa was the most prevalent species, identified in 53 individuals. Titers were > 1:400 in 38 seropositive individuals. In conclusion, there is a high prevalence of Leptospira spp. antibodies in the area, where it is thus necessary to establish control measures to decrease the risk of environmental exposure to leptospirosis.