Toxocariasis in an infection caused by the larval stage of a nematode parasite, the Toxocara (T. canis more often and T. cati ,rarely), and it is acquired by ingestion of contaminated dirt or food by embryonated eggs of the parasite coming from animal feces. The aim was to determine whether the presence of a dog and frequent contact with it imply a greater risk for infection in healthy populations without evidence of clinical symptoms of the disease. Method: Using ELISA method, the levels of antibodies against Toxocara canis were determined in two populations: a group of dog owners (183 students in the third year of medical school, between 21 and 23 years old, from different areas of the country who voluntarily submitted for the study, with a dog as a pet) and a control group (30 would-be policemen, aged 20-25, who do not own a pet dog). Results: Out of the 183 samples analyzed from the first population (medical students), 25 were positive, showing a prevalence of 13.67%. In the population with no dogs, the prevalence was 3.33%. Conclusions: Although the percentage of positivity in both populations was low, a higher prevalence of Toxocara canis antibodies can be seen in the medical students, suggesting that contact with the animal favors parasitic infection. Therefore, it is extremely important to educate the population as regards care and veterinary control of pets, and to maximize hygiene measures to prevent the spread of this and other parasites.