Sensitization to laboratory animals (LA) has a high prevalence among laboratory workers. It is unknown whether transportation of LA allergens can be a risk factor for sensitization of subjects outside the laboratory environment. The aim of the study was to investigate the prevalence of sensitization to LA among children whose parents were and were not occupationally exposed to LA. The first group consisted of 50 children (age 12.3+/-4.3 yrs) whose parents were occupationally exposed to mice, rats and hamsters. The second group consisted of 40 children (age (mean+/-SD) 10.8+/-3.0 yrs) whose parents were not occupationally exposed to LA. Children having LA at home were eliminated from the study. All children responded to a questionnaire, underwent spirometry and were also tested with skin prick tests with the use of common allergens and prick tests with hair extracts from mouse, hamster and rat. Total immunoglobulin (Ig)E levels and the presence of specific IgE against LA were also estimated. Children of parents occupationally exposed to LA presented significantly more positive skin prick tests against allergens from the hair of laboratory animals compared to children of nonexposed parents. Five children from the first group were also found to have specific IgE against LA, with three of these five children complaining of rhinitis and cough while visiting their parents' workplace. It is concluded that the observed increased sensitization to laboratory animals among children of occupationally exposed parents could be the result of poor hygienic conditions at their parents' workplace. Hence, parents' job seems to be an additional risk factor of sensitization and should be taken into consideration when recording an allergic history.