The aims of the present study were to assess the prevalence of Toxocara infection in household cats and dogs, together with the presence of anti-Toxocara IgG antibodies in humans and the level of egg contamination in soil and vegetable samples from the local environment. Prevalence values of 47.8% of 253 cats and 37.7% of 284 dogs were recorded, together with 35.8% of eggs in soil samples, 25.0% in garden vegetables and in 56.3% of 16 dog-hair samples. The risk of the infection was higher for dogs and cats in households with egg-contaminated soil compared to those without evidence of soil contamination. The high prevalence of dog and cat Toxocara infection and their indiscriminate defecation behaviour contribute to a significant risk of transmission to humans as 58.7% of human blood samples were seropositive for Toxocara. Anthelmintic treatment of dogs and cats, plus educating household members, must be emphasized in any prevention programme in Vietnam.