The aim of the present estudy was to determine the epidemiological factors of toxocarosis in Gualeguaychú, Argentina. It was evaluated the seroprevalence of this parasitoses in 272 healthy blood donors (ELISA test), and the relationship of this parameter with the socioeconomic conditions of persons, presence or absence of parasitized dogs in their dwellings and sorroundings; and the contamination of publics places of this city with Toxocara spp ova. The seroprevalence was 12,13% with most of the individuals being asymptomatic. Neither socioeconomic status nor dog ownership correlated significantly with positive serology. Toxocara canis eggs were found 25% of the dogs studied and in 100% of relevated public places. It can be therefore concluded that there is a high frequency of contamination in the soils of public places with T. canis eggs, as well as a high percentage of dog infected with this nematode. This situation establishes an important risk to acquire toxocarosis for the inhabitans of this city.