Animal welfare organizations receive hundreds of calls each year asking for advice on rehoming pets from the parents of children who have - or are at risk of developing - allergic diseases. But if a child reacts to the allergens produced by domestic animals, is it necessary to avoid any further contact? On the contrary, there is mounting evidence to suggest that keeping a pet may be just what the doctor ordered for a child with an allergic condition like asthma. John Bonner looks through the literature.