Background: Humans may be accidently infected by larva stage of Toxocara canis and Toxocara cati nematodes through consumption of contaminated vegetables and food by embryonated eggs and geophagia. They cause visceral, ocular, and neurological syndromes detected through serological methods. Parasitic contamination and infectious diseases are the main cause of eosinophilia. Objectives: The current study aimed at investigating Toxocara canis seroprevalence in military personnel and their families with eosinophilia referred to a military hospital in Tehran, Iran, from 2015 to 2016. Methods: In the current cross sectional study, 179 patients (military personnel and their families) referred to a military hospital with eosinophilia > 5% in a two-year period (2015 -2016) were selected and after obtaining informed consent and filling out the questionnaires, anti-Toxocara canis IgG was detected in their sera using the enzyme-linked immunosorbent assay (ELISA) technique. Results: Seroprevalence of Toxocara canis infection was 11.7%. Males were the most infected individuals. After statistical analysis, a significant relationship between the level of education (P = 0.01) and history of pet contact (P = 0.02), and anti-T. canis IgG was found; nevertheless, it had no relationship with age, gender, occupation, and place of residence (P > 0.05). Conclusions: Prevalence of Toxocara antibody was relatively high, which can indicate susceptibility to Toxocara infection in military personnel due to military operations. Due to lack of clinical manifestations in some patients, survey of Toxocara infection in eosinophilia cases is recommended.