To describe the principal evidence in the literature regarding the interrelationship among helminth infections, atopy, and asthma, a nonsystematic review of the literature was conducted. Among the publications on the subject, we found a number in which there was controversy regarding the capacity of geohelminth infections to inhibit responsiveness to skin allergy tests and to minimize the symptoms of allergic diseases. However, although small in number, studies of patients infected with Schistosoma spp. suggest that these helminths can inhibit the responsiveness to skin allergy testing and minimize asthma symptoms. Evidence provided by in vitro studies suggests that helminthiases inhibit T helper 1- and T helper 2-type immune responses. This opens new therapeutic possibilities for the treatment of immune system diseases.