This cross-sectional study was carried out on 1210 randomly selected schoolchildren, attending sixteen primary and secondary schools, during the period between November 2005 and June 2006. Parents who accepted to include their children were requested to be present at sampling time and to fill in a simple questionnaire with personal and epidemiological data. Three milliliter of venous blood were taken by vein puncture under sterile conditions from each subject for detection and titration of antibodies to T. canis and eosinophil counts. Total IgG anti-Toxocara antibodies was evaluated by T. canis IgG ELISA kit. According to the manufacture recommendations, an index positivity >11 U was considered positive. Of the 1210 serum specimens tested, an overall seroprevalence for Toxocara antibodies of 25% was obtained. There was no association between positive seroprevalence and age (p = 0.34). Boys and girls differed significantly with regard to Toxocra titre (p = 0.003). Eosinophilia in peripheral blood (> or = 5%) was detected in 24.5% (297/1210) of the population studied, 97/297 (32.8%) of whom were seropositive for toxocariasis. The findings of this study confirmed that infection with Toxocara is quite high and widespread in children in Northern Iran. Therefore, health promotion efforts must be directed at increasing the awareness of the population about the potential zoonotic hazards associated with the disease and how to minimize them.