Background: Toxocariasis is a zoonotic geo-helminthes infection with reactive respiratory changes occurring in response to its larval migration. The aim of this study was to determine the Toxocara seropositivity in asthmatic children and to assess its relation to clinical signs, laboratory tests and epidemiological risk factors.Methods and findings: 120 asthmatic and 60 non-asthmatic children were included in the study. The anti-Toxocara IgG antibodies were investigated in all serum samples using ELISA. The Toxocara seropositivity was significantly higher in asthmatic group than the control one; 84% and 16%, respectively. There was significant difference between both groups regarding IgE level, eosinophilia, geo- eosinophilia, geo- geo- phagia, splenomegaly and hepatomegaly with no significant difference as regard gender, locality, lymphadenopathy and contact with pets.Conclusion: Toxocara infection should be considered as a potential environmental risk factor inducing asthma among children population in developing countries.