A total of 142 serum specimens from Croatian children aged 3–18 years, with peripheral eosinophilia and without any clinical symptoms, were tested for the presence of Toxocara canis IgG antibodies using an enzyme-linked immunosorbent assay (ELISA) and Western blot method. The overall T. canis seropositivity rate in the samples tested was 31%. There was no statistical difference in the seroprevalence rate between boys (32.1%) and girls (29.7%, χ2 = 0.092, P = 0.761). The T. canis seropositivity varied significantly between age groups both in boys (Fisher's test P < 0.001) and girls (Fisher's test P = 0.007). The highest seroprevalence rate was found in boys aged 11–14 (42.9%) and girls aged 7–10 (44.2%). Our results showed a high seroprevalence rate of T. canis infection among children with eosinophilia. It is important that testing for toxocariasis should be included in a differential diagnosis of eosinophilia, especially in children.