The objective of this work is to define the prevalence of IgM and IgG antibodies against Dirofilaria immitis in an exposed human population. 395 individuals attending primary care facilities in an area endemic with canine dirofilariasis were studied, as well as 100 non exposed individuals. An ELISA method was used for the detection of IgG and IgM antidirofilarial antibodies. Sera were preadsorbed with antigens of Toxocara canis, Ascaris suum, Echinoccocus granulosus and Fasciola hepatica to prevent cross reactions. Global seroprevalence was 9.3%. IgG antibodies were observed in the oldest sector of the population, while IgM antibodies were found only in its youngest half. No sex differences were observed. This result show that dirofilariasis is common in humans from endemic areas. Repeated contacts with the parasite are common and begin at a young age.