Background: Toxocariasis is a widespread zoonotic disease caused by the nematode Toxocara canis. In Venezuela, the magnitude of the disease is unknown and seroepidemiological studies have not been previously carried out in Aragua state. Methods: A cross-sectional field study was conducted in eight preschools in three municipalities from Aragua state in Venezuela. A total of 224 children aged between 1 and 6 years were studied (43.8% [98/224] male and 56.2% [126/224] female). Blood samples were obtained for detection of IgG antibodies against Toxocara spp. using ELISA. Participating families were given a questionnaire and children included in the study were clinically evaluated by paediatricians, and signs and symptoms observed were included in the questionnaires. Results: Anti-Toxocara spp. antibodies were detected in 29.0% (65/224) of children. The seroprevalence in the different preschools studied ranged between 4.2% and 60.6%. Leucocytosis and eosinophilia were also detected. Analysis of questionnaires indicated that boys were more at risk than girls. Younger children were also more at risk. Other significant risk factors were socio-economic strata (IVand V), inadequate improvised housing, earthen flooring indoors and outdoors and the presence of dogs in preschools. Conclusions: The results from this work show the presence of infection and a high prevalence of antibodies against Toxocara spp. in the studied municipalities and indicate that toxocariasis poses a serious health problem to preschool children in Aragua state.