Toxocara infection is associated with an increased prevalence of airway symptoms and may be a possible aetiologic agent of chronic cough. The occurrence of toxocariasis in Hungary is mild and/or sporadic. The purpose of this study was to investigate the levels of serum cytokines (IL-1, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IFN-gamma and TNF-alpha) and total IgE, the blood eosinophil count, the results of skin prick and non-specific bronchus provocation tests in Toxocara-seropositive children with chronic cough relative to those in healthy controls. The patients exhibited moderate eosinophilia, significantly elevated levels of serum total IgE, IL-6, IL-10, IL-13 and IFN-gamma, and higher skin reactivity to common allergens, whereas the bronchial hyperreactivity was similar in the two groups. The protective proinflammatory cytokines (IL-6, IFN-gamma and IL-13) in association with the anti-inflammatory cytokine (IL-10) were simultaneously increased in Toxocara-infected children with chronic cough. During infections, the activation and suppression of immune processes occur simultaneously and cytokines of Th1/Th2 and regulatory T cells contribute to the regulation of the immune response evoked by helminth infections (depending on the parasite load, the timing and duration of the infection and the status of the host immune system).