The objective of this research was to determine the prevalence of leptospirosis in humans in the urban area in Puerto Libertador, Cordoba, in the Caribean region of Colombia. In august 2007, we used a cross-sectional epidemiological study. We included serum samples from 78 individuals and general information (occupation, exposure to contaminated sources such as water or animals). We analyzed those samples through microscopic agglutination test (MAT) with six serovars of Leptospira. Anti-Leptospira antibodies were found in 67.9% of the sample, in patients older than 20 years, with no significant differences in the sex variable. Among six serovars tested, the antibody titers were high, especially L. icterohaemorragiae. The high prevalence of serovars in humans in the urban area in Puerto Libertador suggests frequent transmission of leptospires, whish is relatedto the presence of rats or mice in homes, outdoors and cisterns of slack water channels.